For my purposes these things are toys. I use both triangular FE A1 and round FE A2 20s at MG shoots. I find no significant differences in controllability during FA as a function of either: handguard type or barrel profile. This may sound odd given the heavier profile of the A2 govt barrel. I also find no difference in terms of precision, pointability, or comfort level.
FWIW, the big aperture on the A2 sights are an advantage during FA - allowing the sight picture to be easily maintained through mag dumps. The best combination, IMO, would be A2 apertures on the simpler A1 receiver.
The LMG upper is a different kettle of fish, stable enough with even a small aperture. But note that it has a rectangular forend..........again, neither an advantage nor a disadvantage during FA, IME.
Both forends have "cool" factor.
Sam