Yep, I am a die hard valve lover, but I agree there are lots of pros to modelling amps, the first one
Fun
My modelling amp cost $240 and it was worth it just to see my friends face when I hit the footswitch and broke out into the harmonized lead from Detroit Rock City all by myself
Lots of other good reasons to have one, if you play gigs long enough with a valve amp at some time you will hear a horrible whining sound and you will look around to see smoke coming out of your amp, you have about 5 seconds of sound left. Unless you have your moddeling amp close by, then you simply plug that into your speaker or the PA and keep going. I wish someone had told that to Steve Stevens before his amp blew as Billy Idol was tearing towards the stage in a hovercraft at a football grand final some years back, biggest Wah, Wah, Waaaah I have ever seen.
I love my Marshall valve amp so much I am married to it, but I know it's a prehistoric relic made for an age where bands played huge halls with only a vocal PA. 100 watt valve stacks are ridiculously over powered for most uses these days (perhaps that's what I love about it). And I agree with you Guitar2005 that a smaller head like the Blackstar 20 is a great option.
The Vox Tone lab does sound good, you know its a modelling preamp with a single 12AX7 in the preamp stage, exactly as the Marshall JMD has a modelling preamp with a 12AX7 in that stage.
I agree with Tim also, valve amp versus modelling amp doesn't have to be an either or situiation, you only live once, spoil yourself, get one of each