Can someone please shed some light on the advantages/disadvantages of this mixed strategy?

In terms of both netting and warring.

There are no advantages because the Indy and Farmer strategies each require their own tech (industrial and agriculture respectively). Going half and half means splitting your tech base in half, which is not as efficient (production-wise) as going fully in one strategy.

Xin has this one covered

Yup, what Xinhuan says!

Always focus on one type of building, 50/50 strats will always be worse. Well, except for cashers though ofcourse...