FIFO
I just think FIFO will eventually flatline the market (it will take several sets, and of course further game changes are going to influence this and may well hide the repercussions as has most the changes we've witnessed). There is no reason to solidify a high volume mark (peak price where everyone can see without the need for boxcar analyses), so FIFO would taper down the market fluctuations. It also makes crashes more dramatic, which restricts selling off when dumping/jumping. Prices will drop far too quick for players to utilise skillfully, rather it becomes a game of luck and who's willing to sell even cheaper (good only for market plays but not general trends caused by strat changes such as stockpiling and jumping as prices will hit their min/max values very fast).

This set, the private military changes, the military tech change and losing the cap reduced market nuances, as cash can be held on hand much easier, and players are being encouraged to use the private market for nearly everything. The preplanned war also contributed significantly to everyones play styles and creating the market we had (which I thought was very poor at showing fluctuations in what has been happening due to the players… there should be bigger indicators and the market should respond directly with what players are doing, be it war, or switching between phases of a strat - it should be seen in the market, particularly with so few players in the game (this current market is a response to all the new changes and just looks boring)), but FIFO has also been a contribution to the market differences we have noticed. You really don't want players to interact completely independent of each other… everyone would hate that.

LIFO
All it really does is let you sell first at the first massive block price. If you need it to sell you sell lower. The point is to be able to get to that first marker or high volume price and prevent those on the market from going further (which would release goods that are backlogged over 2 days and create potential market plays). Most good players will not buy at the maximum prices, and can now place items on standing orders, which works better still without the $2bil cap. The bigger picture is that more players will see the high volume price and react to it and play accordingly to their strat and comfort zones. I think it helps subtly by revealing the high volume price more often for everyone to notice and to consider in their play. FIFO just can't do that, as it encourages players not to sell at that price but lower ( I said that coz it contradicts qzjul but also makes just as much sense) or higher (depending on amount present) and never show a reliable high volume mark players can work with. I would rather sell goods at the high volume price than $X below/above it because most players won't be looking at all the market details to what is cheap/saleable, and simply buy until they hit a high volume mark or spent what they need. I'd want it to supplement the high mark and have players consider their options when they are more likely to see that price to create an another player based fluctuation to the market in the game. Having LIFO is a reason to reveal that high volume price, otherwise I'd sell lower.

So LIFO helps generate high volume points with which players can devise tactics around. Planning a little market stunt in 4hrs is always fun, and now that you've removed the $2bil cap, is more likely to happen. Why not facilitate this activity with LIFO? You'll require to learn and develop a skill in reading the market for the game, and then develop tactics and even strategies around it. What's not to like if LIFO can do that? Recall also becomes a valid gameplay device rather than a safety tool or emergency button, although I'd still like a safety switch for it. It would diversify play, by providing focus for playing on the market. We all play that market, and adding a little skill in playing it will steer us from boredom. I like playing the market, but it doesn't just benefit me, it benefits whoever wishes to play that way and it doesn't really cause anyone to lose out - you've got recall now anyway (here is another potential tactic).

Now the only reasons I see for the change to FIFO, was that it seemed illogical and unfair. Unfair in the sense it takes 4-6hrs to reach the market, but someone else could have sold later and their goods arrived on the market earlier? Illogical because a player has a right for sale in a predetermined order? What right? I dunno, I figure some randomness somewhere like here would help the games survival. FIFO is just better for players on the individual level, where it is one less aspect to think about (in a sense like expenses, we don't really bother too much with it etc). There's a perceived unfairness which is really just as much as any random factor you've incorporated into the game.

It may seem like one tiny change, and it really is insignificant, but it could be a major aspect of gameplay and hopefully I've illustrated some other points for you to add gameplay to.
Affect is minuscule to the short term play cycles, but I think a certain dynamics have been lost when we switched to FIFO. I have devoted a lot of time playing strats around the market, I've been playing around with this little feature of the game for just as long and enjoy it the most within the market. I missed it this set, although the military tech changes were far more drastic to the market. it's a shame to see this aspect go. I'm probably one of your more avid market players, so I hope my opinion is worth considering because I think LIFO is and has been better for the game and would like it back.

A tiny thing that I felt shouldn't have needed to change, but I'd also like to add, I'd prefer the $2bil cap back, and would like the market time of goods extended back to 72hrs (to do with backlogging goods and time it takes to return beyond a high volume mark - this is also a good indication of a returning market above it and clues to push prices one way or another). It was shortened when the turns shortened. I like the 4-6 over 6-8, a 2-3hrs would be far more interesting. Goods need to hold on the market a little while, and the recall function isn't worth waiting 2 days (excluding those times like war), so with 3 days there are reasons to recall other than mistakes or war). I think a cap, any cap is needed to force people to stockpile some how on the market and give it a certain volatility (although no cap tickles my thoughts for a huge market play of some kind…).