Yes, the Triaxis with the 2:Ninety power amp nails the sounds of the IIc+ and the Mark IV, and other Mark-series amps along the way. Like jaquetapus said, if you like Petrucci's tone, you'll find it here. He used to use the Triaxis/2:90, used the Road King for a while, then switched back to the Mark IV, whose tone is found in all versions of the Triaxis.
You'll also get the Carlos Santana type of Mark-series tone if that's your speed... or Metallica, as this is part of James Hetfield's rig, too.
Don't count on it for recto tones. There was one revision of the Triaxis that had a recto circuit replacing Lead 1 Red, but due to a parts issue, it is no longer available. It's not worth chasing down that rev used because it's still not going to give you the recto tone unless you pair it with the Rectifier 100 watt power amp. For the flexible tone options, though, you want the 2:Ninety, which has multiple voicing modes (Half power, Deep, and Modern) -- you don't get the deep and modern settings on the 2:Fifty amps, and the half-power is only on the OLD 2:50 power amp; not the current 2:Fifty product.
The 2:Ninety is the simul-class power amp section of two Mark IV amps... stereo, you know!
Also, don't count on the cleanest Boogie tones. Yes, they're great clean tones. But that manual was written years before the Lone Star came out featuring Boogie's cleanest clean, which also appears in the Road King II (but not the orig. RK).
I have a Triaxis rig and an RK II rig. The recto tone is a different animal. Can't beat the triaxis flexibility, though the RK II comes close.
Scott