The FGS is still the PvE combat king. Nothing shreds a CZ better than full dakka in an FGS. It also has exceptional armor and the low shield values are complimented by exceptionally fast recharge.
You should not be running guardian shield boosters on this ship, nor prismatic shields. Without those two things, I can't see anyone exceeding the PP limits with G5 armored monstered PP.
The FGS is a hybrid, not a shield tank, slap on a biweave and and just think of it as a 250mj heal every approximately minute and a half.
Only the challenger and Krait mk2 (and Python, but meh...) can compete with the FGS for the combination of firepower/defense. The challenger is only half a small hardpoint lower on the offensive side, and the Krait only half a small hardpoint stronger. The FGS has better armor than the Krait (but not the Challenger).
This means that on paper (for PvE use) the Challenger is 'slightly' superior, largely due to its speed and agility by comparison, BUT...the FGS can carry a fighter, and has a medium hardpoint where the challenger has a small, which means that hardpoint damage is compounded against larger ships. The Krait is slightly better for taking on highly armored larger ships, aain due to the average size of the hardpoints providing better bonuses against larger ships.
See, it's all pretty well balanced. FGS is in a good place and is still the ultimate battle ram. Fit it with 7 multicannons or you're doing it wrong. Enjoy.