Exactly! I'm having similar thoughts, my rig is killing me! It a monster (Fractal Axe-FX II >> Mesa 2:90 >> 4 ohm out into 2*12 and 4*12 (6 speakers total) Recto cabinets.
I would be curious to hear your review being you are also a 2:90 user.
Also, what are you using for cabs? I'm thinking of going all the way and getting new cabinets (FRFR).
The Matrix is close enough or me to make the switch. My concern was the brightness. I noticed that there's a slight decrease in low end. But it doesn't matter since at rehearsal when I was using the Mesa Boogie I had more than enough low end ,so a mild decrease will not bother me.
As far as speakers I'm using 2 Scumback BM 75 100 watt version 8 ohm each. I have 2 Marshall 1960B, one with Scumback's H75 and the other has V30 which I'll be replacing with 4 BM75 60 watt 16 ohms. I also have a custom Marshall style 4 x 12 cab built by Scumback with 1969 specs but it looks like my 1960B cabs with Scumback's M75.
I usually use my Marshall with H75 with the 2 x 12 with BM75. So like you, I'm getting a total if 4 ohms since the Marshall in stereo which is rated at 8 ohms so together with the 2 x 12 and can get more juice out of my amps.
I sometimes use 2 Marshall cabs when the gig is bigger and my band members are so cool that they carry my gear for me.
The problem is that when I get home I have to carry my gear into my studio and I can't expect them to drive to my place!
The Matrix puts out 500 wpc at 4 ohms so it should more than match the loudness if the 2 90. It sound much better than any other SS amp I used and close enough like the 2 90. But since the Matrix occupies 1 rack space and weighs 8 lbs I'm willing to deal with the small difference which can be corrected by using the global eq.
Anyone who says that it sounds better than the 2 90 IMO have no clue what they're talking about! But it sounds close enough for me to make the change! I wish they could incorporate a presence control.
There's an amp that simulates a tube amp that I forgot the name, but it's a 2 space amp and it still weighs to much.
If your sick of carrying a tube amp I believe the Matrix is a great alternative, but if carrying a tube amp is not an issue for you then keep your tube power amp. Is true that the Matrix is very flat sounding amp and the other reason why I got it is so I can make my own IR's since I didn't like the 2 90 for they specific application.But I'm really impressed with the Matrix because they manage to make an amp that's very powerful, it's only 8 lbs and it fits in 1 rack space. I believe there's nothing out there that can compete with them.
As far as FRFR, I'm not sold on using IR's yet, I know there's a lot of people that would disagree and I can se the potential, but it's hard to teach an old dog new tricks and I enjoy having my Marshall's behind me.
There's no way that 2 active full range speaker cabs can't compare to 6 to 8 12" speakers or 4 Marshall cabs, it's just physics! Unless you use a sub or 2 FR speakers with 15" LF drivers. But that's just my opinion.