I mean....
After careful consideration, yea should FDev nerf the FdL and FAS. If they do that, the Vulture, Python, Courier, Clipper and Gunship all become relevant again. Hell you might even see a few Cobras. And the Cutter/Corvette/Conda can't be forced out of a PvP fight in 20 seconds like they can be now, because there won't be a high volume of ships firing QUAD Rails.
Yea, suddenly most of the combat-capable ships become viable options.
I say revert the power plant changes. FdL's were strong when all they had was multicannons + C4 PA. Keep the pitch rate upgrade. Give the FAS a similar power plant nerf and/or an armor nerf. I'd also suggest nerfing the pitch rates of the Corvette and Conda to be closer to the Cutter (but still faster) . Right now they're about 50% faster in pitch than the Cutter. Make them only 25% faster. Make those big ships more reliant on turrets and gimbals. No reason for the biggest ships in the game to be able to turn damn near as fast as fighters. balanceblancebalance.
Believe it or not I rewrote this entire post, dumping 2 paragraphs because I originally wrote against nerfing...then I realized I was wrong.