What most people forget is, and what usually puts them off when they hear modelers is, the fact that they are not supposed to sound like an amp that you're standing in the same room with. They are supposed to sound like an amp that is being mic'd in a separate isolated room, and you listening to it in a separate room through a pare of monitors. If you're playing live, the sound that the audience hears coming through the FOH will not be what you hear on stage with a real amp. It will be an interpretation of your amp, through whatever mic is being used, through the mixer, then to the FOH speakers. So, unless you're playing at a venue where your guitar will not be going through a PA, then there is no audible advantage over using a real amp to using a modeler... the sound that the audience hears will be the same either way.

However, if you're not happy with your tone, then you're playing will most likely suffer to an extent. So, use whatever gives you the best practicality to tone ratio. ;)