the microcube is a fine little amp for bedroom practice. and the battery capability is cool.
in terms of real tone though, modelers don't even come close. i mean not even freaking close. you wouldn't want to be caught dead playing one in any live situation. they are useful for recording in apartments but other than that and damage-control type studio band-aids, they have no professional applications. as for hybrid amps, i used to play a marshall valvestate and i thought it was great until i had an hour alone with a real tube marshall. i went straight out and bought one for myself. so. much. better.
fritzo, your tube problem was caused by microphonic tubes. a simple switch to a set of tubes that didn't suck would have cured it. many people actually consider the old marshalls and mesa boogies to be more reliable than the new ones. i have a new one and it hasn't given me any trouble after several years of heavy gigging, practice, marathon recording sessions with the volume pegged at 10, etc. but the first thing i did when i bought it was change the tubes. the stock ones were microphonic, just like fritzo's. and i understand proper tube biasing, warm-up/cool-down procedures, etc.
as for software modelers: if you compare modelers from the same company, you're getting the same models, so it will sound the same. the software is probably a little better because you're not dealing with that extra D/A and A/D conversion. you do need a direct box (DI) to properly feed them, unless they come with an input box of their own. amplitude is probably the most commonly used set of modelers in pro studios. but most engineers consider modelers an emergancy backup solution rather than a "ok, time for guitars, let's fire up our modelers!"