Have you played a mark series amp before?
IMO, it does a very good mark 2c+ TONE. The biggest difference with the triaxis, in my opinion, is how it feels when you play. It does not feel like my other mark series amps (mark 4 and quad pre). That being said, I think my quad and mark 4 overlap, so I may be selling the quad to pick up a triaxis, if the prices come down on them.
I would not hesitate on buying a triaxis based on the tonal differences between it and a mark series, because they are more similar than different.