Your move, Line 6! As a valve amp enthusiast over the past 10 years I've played a whole range of lovely amps, but after an accident last year I sold off everything thinking I'd never play again. After some rehabilitation I was back looking at the amp market for something in the budget range as funds aren't great now.
For under £300 you really can't beat this. Almost perfect power-amp-saturation emulation here, my favourite crunch sound out of it is the 'Warm Clean' with all the dials cranked up! Really emulates that 'small-amp-on-10' sound, with all the dynamics you'd expect from a valve amp. The high gain sounds are huge, and as far as the EL34, 6L6 and EL84 emulations go (the amps I've had the most experience with) they really do sound like the real deal. I've never played any KT66 or KT88 amps before, but I really do love the sound these emulations put out.
The effects are nice, reverbs take a bit of tweaking but there's a lot you can do with the simple controls. This smaller combo is lacking a mid control on the EQ, but from what I've found the ISF can give you some decent control on the mids anyway...if in doubt just turn it all up and let your fingers do the talking!
There's only one real niggle with the amp and that is that the channel switching using the FS-10 footswitch is not as instantaneous as I'd like it to be, so I wouldn't use it on a live gig if I needed to change sounds quickly. Luckily I prefer the single channel approach using the volume knob to get my different sounds so its not a deal-breaker for me.
All in all, Blackstar have once again proven that they really know how to make a great amp, and the price is just ridiculous for what you get. I was close to just buying a Line 6 Spider, but after getting this there really isn't any point even thinking about it! If you want a ton of great sounds in a small, light and affordable package, you can't go wrong with this amp ;)