Runnin, 250W would be nice if you can get it for the same price as 100W but if it is more money than perhaps getting better 100W (better design, better components) would bring more satisfying sound.
Bifwynne, Local feedbacks are better. Even emitter (or cathode) resistor is a form of NFB. SS amplifier, being voltage source, needs feedback at least for the output stage. Tube amps, being power source, most likely need less of it.
It is possible to design amplifier with negative feedback free of TIM. Since problem of TIM is caused by summing fed back delayed signal, during fast transition, it would be logical to prevent fast transitions and to eliminate delay. It comes to bandwidth limiting input stage before summing point and extremely fast output stage. High quality parts have to be used to achieve good initial linearity and wide bandwidth. NFB should be mostly local but also shallow just to bring THD distortions to about 0.5%. Bandwidth should be limited at the input to one that amp had before feedback was applied (since NFB widened bandwidth).
Such amp will have 0.5% THD and perhaps only 50kHz bandwitdh not to mention relatively high output impedance. THD distortion is not that audible, 50kHz bandwidth is passable and output impedance doesn't matter because inductor in series with the woofer is about 0.1 ohm (limitting DF to 80) while speaker impedance (being source impedance for back EMF) is mostly resistive.
Would you buy 100W amp with THD=0.5%, 20-50kHz, DF=50 when somebody else is selling 250W with THD=0.01%, 20-200kHz, DF=1000 ?
Specifications are useless - only sound matters. All comes to good design, quality (expensive) components and smart compromise.