I've been using a Line 6 Spider 75 this week for a couple of small gigs and on the whole it's been fine. It does tend to be a little directional and competing with a Randall heac/cab had to be cranked pretty high. Did a good job and was easily workable though and i was complemented on a nice sound.I may have failed to mentio nthat this modellign amp will most definitely be seeign use live very frequently. My friend is already using his Line 6 Spider III there and it's doing fine.
A 5-watt Blackstar might not have what it takes to handle live gigging... not too sure lol.
And I tried out the Vypyr for 2 hours and if there were massively different sounds available, I couldn't find any. Also, the amp seems far to complicated to switch between sounds live.
My advice is to take your time and try as many as possible, there's a world of stuff out there and you're guaranteed to find something which you love. Borrow something short term and shop around as much as possible. Also remember that the sound practicing will be different to playing live somewhere and your miking skills will be tested! I like my little 6 and it's worked well for little cash but will definately upgrade to something more serious as funds allow. Cheap Mesa anyone???!!