I’m wondering how many people would welcome the addition of a final EQ stage right at the output end of each plugin. After all the other processing including cab simulation and microphones.
The reason for this would be to compensate for differences between your own selection of headphones, speakers, PA etc. Having spent ages developing your own perfect collection of presets which sound just right in your headphones, a switch to PC speakers or a PA so everyone else can listen might leave all of your presets sounding too bright, too bassy etc. A single stage of EQ (a copy of the standard 9 band one already included would be an obvious choice) which is part of the Settings menu rather than changed with each preset could compensate for this. It would then need it’s own set of presets to allow an easy switch of output device.