I hope it is something different, really can not read about all good ideas here. Instrumentation amplifier is very stabile way for handling amp inputs, and with some modifications could be used as additional gain source used for negative feedback. If assembled of two similar opamps with similar phase shift, simulators shows that it is easy to compensate circuit only with adjusting c2 and c3 on attached schematic. U1 and U2 shows err correction circuit with U4 (which should act as gainclone together with q1...q4) embedded in feedback loop. As gainclones can sound as serious amplifiers I expect this modification to make them even better. Every suggestion is welcome, hope I'll succeed with prototype to show you results .