IMHO, some of the models in the upcoming release sound better than the real amp. I tune some of the models by ear after entering the data. It's MUCH easier to tune a virtual amp than a real amp. With a real amp the designer has to tune the amp by unsoldering parts and putting in new ones. This is tedious and time-consuming. In debug builds I can tune the amp with a twist of a knob (the parameters are not exposed to the user in release builds though). The beautiful thing about the Quantum algorithms is that they are basically real-time SPICE models so I just turn a knob to change a resistor or capacitor value and I can hear the results instantly.
Of course this assumes that my preferences are "better" but I think they are. I spent most of last week "Quantumating" the amp models from a certain European manufacturer. IMHO, the tuning on those amps are not optimal which causes a lack of clarity when playing lightly or rolling off the volume and a lack of string separation when playing hard. So I tuned them slightly to improve clarity and string separation.
I never deviate drastically from the originals but some amps can benefit from minor tuning.