well, feel is hard to describe, its how an amp repsonds to your dynamics, picking techniques, touch just the finer points... and by resposne that covers compression artifacts, overdrive characteristics (and I don't just mean overt drive like a pedal, I eman something else as most tube amps are creating subtle harmonic distortion even when you think they are set clean, most speaker designs for guitar add some THD too even at 1 watt).... I am having trouble talking about this as its hard to explain. An amp with great feel is like an extension of your guitar.... an amp with poor feel is like plugging into your dad's stereo, the instrument ends at the output jack and you can't play the amp and speaker, it has no feel
on a side note, those guys drive me nuts, total sales people who spout things like 'great feel' because they've read people on forums say similar things and decided to use those words to sell ya stuff... or at least that's my impression of them, at least Rob can play some (though he's really heavy handed when he does anything non metal), the Capt is a truly terribly musician
feel is ahrd to define but hard to miss when you put 2 amps next to eachother.... all 5 of my ac30 type amps have different feel... same basic type of sound but they feel way different so apart from the subtle tone differences from amp to amp I play them differently, I just do different stuff even with the same notes through say the '62 and the reissues and even different still through the arbiter that's way stiffer and aggressive
I am just talking apples to apples here, start comparing Hiwatts to Voxes or something like that and the sound might be similar at times but the feel is way off, the hiwatt is firm, Hifi, bold, the vox is buttery, fast but sometimes spongey, hard to explain
maybe get some very different amps against eachother and just try playing some licks into them one after another enxt time you hit a guitar store..... maybe do a solid state modelling amp, a good Marshall (plexi or 800 reissue?), a blackface fender RI, an ac30 and a modern amp like a mesa or a blackstar....g et the frequency response and levels of gain/vol close on all of em and then have at its and feel the magic