Well a quick google search on the Blackmore tells me it doesn't have separate EQ for each channel.
Is there any particular reason you are looking strictly at just the Mesa and Blackmore?
The ENGL Screamer I had didn't have too much treble. Granted, it was quite bright, but not uncontrollably bright by any means.
And yes, using a £10 Marshall/Laney/e.t.c. footswitch with the ENGLs works fine, so that's not really an issue.
As for VHT- "are they versatile" is a very broad question. Obviously it depends on the individual model, and how many sounds you are hoping to get. A VHT Pitbull might suit you - (Never tried one myself though unfortunately!)
http://youtube.com/watch?v=sBK__6AgDr8