I have a compressor, and never use it anymore. Used to be amazingly useful when I played a lot of RHCP. Excellent for going from picking to full chords (Frusciante uses a loud valve amp, smoking my MG250 at the time).
Like Indy said, all about the dynamics man
I shall get a try of the Vox V847, they don't have a dc adaptor though do they? Any other models I should be on the look out for? I'll be trying these all out before my gf splashes out, so just want to whittle down my search.