Thusters + shields (thermal res lodraw biweave) yes, but not thrusters + shields + distributor (9.75 MW > 24.0 MW x 0.4).
And if you're forced to stall (no boost) without distro you're as good as dead because you'll be a sitting duck for PA (shadow)rams.
Low draw would be more resistant to bottoming out ENG, but even fast charge thermal resist shields fit in the power limit.
A PP malfunction during shield rebuild on a ship that can power the generator but not the distributor means you have frozen distributor pips for 10 seconds (five second PP malfunction, five more for the distributor to power back up)...that's definitely worse than being able to keep the distributor powered, but still way better than losing all the progress on shield rebuild.
The point about a PP size class reduction potentially harming hybrid setups more than shield focused ones is a good one, but without looking at combat balance as a whole, hybrid setups are often non-starters in unrestricted encounters due to how vulnerable modules are.
Still I 100% sure would rather fly a 2 booster biweave FDL instead of the Chief in the ongoing RoA League, were it not banned. Not because it would be OP (it wouldn't), but only because of the much better and more enjoyable flight model. Oh, and it would be effective as well, ofc.
What else is banned in the current RoA league? Most organized PvP has restrictions to compensate for a whole slew of imbalances that exist. Both the Chief and the biweave FDL are in trouble against someone with an emissive pulse laser and some seekers/packhounds.
Anyway, an artificially handicapped FDL still being effective against a Chief isn't any argument for the FDL being balanced, even if one of the adjustments I'm advocating isn't applicable in this scenario.
If the FDL had a c5 PP, you'd still be perfectly able to use the c5 prismo + doublebank with 5 boosters and 5 PA's (2916 MJ + 2x4A rapid banks).
It would even be easier to proc TC because you'd need a G5 OC PP.
Only if you insisted on using rails would force you to give up on some shield strength (so no 4+1 and 3+2 builds with the same shield, but those aren't really superior anyway).
Someone having rails can become pretty mandatory against larger targets with larger banks. There are also other configs that push power past 30MW...especially if one is using SRB PAs instead of efficient, which were an increasingly common setup for ram focused ships last time I was fighting people regularly. I've even seen a quad SRB rail + huge LR thermal vent beam loadout put to good use on an FDL that went all in with six boosters.
A PP size reduction certainly wouldn't stop front loaded FDL setups, but it might introduce enough trade-offs to skew selection slightly in favor of other options.
It would be much easier to introduce a "max 4 boosters per (medium) ship" limit. That would bring down the max. shield strength to the 2500 (with OK thermal res) to 2700 (with crap thermal res) MJ range, without the annoyance of unnecessary build restrictions.
This would be an even more arbitrary change and would also affect the Mamba, which isn't particularly unbalanced, even with five or six boosters. The underlying problem isn't the number of boosters, but how they stack, and the fact that every other potential utility is more situational and generally less effective.
Ultimately, I'm not suggesting that restoring the FDL to it's old stats would solve all the game's balance problems, but I don't think it would hurt, and it could easily synergize with other changes (stronger negatives, or less profound positives, to Engineering BP's for example).
Original Mamba maybe, but the ED Mamba is quite a bit bulkier than the FDL.