Isolated High Voltage Amplifier Idea
Is the diffpair tail current at least 3X the Miller Capacitance charging current, for 28 volts PP at 100,000 Hz? Otherwise you risk SlewRate limiting. 

===== Linearize the high-gain (bottom transistor) with 10 ohms in the emitter ===

The load is reactive, or even resonant at an unknown frequency. I'd add 10 ohm base resistors in each of the 4 output transistors. And a Zobel series RC from output to Ground.

There will be lots of cross-over distortion. Why not use 5 diodes, and place 4.7 ohms in output emitters.

Place 100pF cap across the 3-diode (Or 5-diode) network.

To avoid sag in the upward-swing output Vout, I'd increase the VDD to 40 or 45 volts, and increase that 100 ohms above the bootstrap capacitor.

The resistive feedback network adds phaseshift to the feedback waveform. The diffpair input capacity, base-emitter-emitter-base, must be charged. 

If the VDD bypassing resonates, life gets tough. And 1uF and 1uH resonate at 160KHz.
10uF and 0.1uH resonate at 160KHz. 1,000uF and 0.1uH resonate at 16KHz. How to dampen?
Use Rdampen = sqrt(L / C) = sqrt( 0.1uH / 0.001F) = sqrt(1e-7/1e-3) = sqrt(1e-4) = 0.01 ohm. Which may be provided by ESR of the bypass capacitor. Or not.

If you use small VDD bypass caps, use two caps in parallel, and place 1 ohm in series with one of the caps. 

Again, the large caps may self-dampen.

By the way, 4" of wire is 0.1uH.