ok, absolute min prices, (100% mb with max tech) are...
_________Theo________Demo
_________25%__40%____25%__40%
Troops____77____62_____88____71
Jets_____103____82_____118____94
Turrets___112____90____129____103
Tanks____315___252____360___288

As well as improving profit on slow selling tanks and troops your change will actually make selling jets and turrets a very worthwhile prospect for an eartly set TMBR - also for a DMBR.

Looking at 10k Theo, 180 cs, 200 ind, 120k mil tech (90.55%) then...

@25%______Private___Public___Units_in_6_hrs__Profit
Troops_______79_______120_______360,000_______12.17m
Jets________106_______130_______300,000_______4.86m
Turrets______116_______130_______300,000_______1.86m
Tanks_______324_______520_______120,000_______19.78m

Total profit = $38.66m
(Demo MBR profit would be $29.58m - no profit on turrets at this price for DMBR)

@40%______Private___Public___Units_in_6_hrs__Profit
Troops_______64_______120_______180,000_______8.78m
Jets_________86_______130_______150,000_______5.43m
Turrets_______94_______130_______150,000_______4.23m
Tanks_______262_______520________60,000_______13.61m

Total profit = $32.05m
(Demo MBR profit would be $29.04m)

@25%______Private___Public___Units_in_6_hrs__Profit
Troops_______79_______105_______360,000_______7.09m
Jets________106_______110_______300,000_______-0.78m
Turrets______116_______110_______300,000_______-3.78m
Tanks_______324_______480_______120,000_______15.26m

Total profit = $22.36m (tanks + troops only)
(Demo MBR profit would be $17.28m)

@40%______Private___Public___Units_in_6_hrs__Profit
Troops_______64_______105_______180,000_______6.25m
Jets_________86_______110_______150,000_______2.61m
Turrets_______94_______110_______150,000_______1.41m
Tanks_______262_______480________60,000_______11.35m

Total profit = $21.62m
(Demo MBR profit would be $17.94m)

[At 60% regen and 40% reductions, profit for
low public prices above would give $25.94m
high public prices above would give $38.46m]

This would, I think, have a small effect on commie indies as mbr would make sales of jets and turrets if they had bought out their tanks and troops.

I have to think more on whether this would be a good or bad thing for full or half set mbr. I think I agree with what you say about late TMBR destocking.