i wouldnt go that far. The Art in particular I owned first with my Axe. it was OK, but only having binding post O/Ps was a nause. also there was always something withthe EQ. The low mids/bass I found too "round" or "thick". it didnt have dynamics there. The highs were alittle brittle but also lacked dynamics. It was what it was - a cheap SS power amp.
The Messa 2:50:2 I tried but as James says, it does have the messa sound. the VHt stuff is more linear/neutral. Its still not flat, but pretty good for a valve power amp, and it does as you would expect offer the dynamics the Art is missing. It just felt much better to play through.
There are many SS power amps out there that would work well, BUt there pretty much all 2u, close to the same weight as a valve amp, and as much if not more money. Think Lab Gruppens, Brysons, top end Crowns, Hafflers etc.
It is, when you can put up with. For me (although I still have one last test to do when I find a location) the Matrix actually ahs the dynamics. it is flat so is slightly different to the VHT, however thats an EQ thing which isnt a problem. The thing that IS important is its dynamic, sounds good, and it very well designed and built. its very cheap for what it is. I ws pointed to 2 other UK amps that are aimed at the same spot in the PA market, and who are directly competing with the Matrix amps. They were both over £1500, and arnt any better.
So, to the question. I guess you get what you pay for. the MAtrix is the cheapest SS amp I have found (and I include the Carvin and Rocktron stuff in there as I have tried those) that actually does deliver. The fact its 1U and light is just an added bonus. If you want tohe best you either get a quality SS amp or a valve amp, but cost wise there not going to be far appart.
Even to the states/Canada the Matrix represents pretty good value IMO, even if its not as cheap (relavively) as it is in the UK, but its your choice. How much is a Messa 2:50:2 or a VHt 2:50:2 in Canada? i dont know Im just asking. i would expect those to be more than the Matrix, though no doubt there are used ones available. if you cant afford the price of the Matrix, then you have to lower your expectations, in which case something like the Art or Rocktron are still fairly good options - there just not the best out there.
at the end of the day, as Jay and co keep saying, a well designed quality SSs power amp is actually preferable to a valve power amp, bu they cost too. why pay $1500 to $2000 on an Axe-FX and amplify it through a $300 amp? Each part is just as important.