Anyone using an understable driver for FH has bad form IMO. Your wrist is not designed to torque that way with a full snap, hence why peeps throw overstable discs for FH. Your losing power by having to tuck your hand closer to your body to get the hyzer angle. Release flat or slight anny to get your distance. You do this with a teebird at full-power and youll end up in the dirt. No one on here knows your form like you do, so take all the advice with a grain of salt, formulate your own decision and try stuff until you find YOUR niche.
Actually, the exact opposite is true. Most forehanders, especially those that don't use it exclusively like myself, have terrible form and use overstable and too fast discs to make up for it. If you're throwing forehand with good form, the disc should not crank so hard to the left (assuming RHFH) that you need a firebird to make it come back. Folks that throw neutral to understable discs forehand need to have better form to keep the disc from turning and burning or becoming an unintentional roller.