I am one of the few people that have had both amps at the same time, although my Tfunk was a 420.
As far as the VLE and VPF vs. the Timbre functionality, I found the Timbre control much more useable. A lot of the VPF and VLE function I felt could easily be obtained by altering my right hand technique and/or onboard EQ changes. The Timbre control does something which I can't do myself.
This is not to say that I felt the Markbass was a bad head, far from it. I liked the Markbass a lot, and I only traded it to try this crazy Mesa I am using. Right now, if I could afford it and actually had reason to have three heads, I would have the Little Mark, Thundefunk 550 and the Mesa M-2000.
And just for reference: