Just bought one ....
I used to use a 2/50/2 with my AFX standard, and as many will know was involved int he Development of the Matrix stuff. I tried the power station and have gone back to this.
Its a better fit than the 2/50/2 actually. The 2/50/2 while being fairly neutral for a valve power amp, isnt flat. The PS, is actually a reactive load (which you dont use when in Power Amp mode) input, coupled with a FLAT response 50w power output stage. Its designed like a valve Hi-Fi amp. This is how is keeps the tone of a real amp when used as an attenuation. The upshot is, it IS neutral (or as near as its possible to get with valves).
Compared to the GT1000.... Well the top end and upper mids are pretty much identical, This is where I thought any improvement would be found. Its actually the bass and low mid response where it shines. There is more weight to the low end and more transparency/note separation. The Matrix actually has more bottom, BUT as its range is lower - and coupled with the high impedance output, results in a rounder bottom with less "clunk" and a slightly more congested low mid range. The PS wins here. On clean tones its really hard to tell the difference unless you do single note "dig ins" and listen REALLY hard. The more gain you put on your patch though, the more the difference shows, and the PS just gives more of what you expect.
So - Ive jumped from Matrix back to Fryette (keeping the Matrix as backup - and will eventually rack both in a separate 4U "Power Amp" rack).
*EDIT* I will say - the Bright/edge and Warm/Deep toggles on the PS have no effect when in pure Power amp mode as there for the reactive load. The Presence and Depth controls do though. Both at noon sound the most neutral, though you can play to help compensate for different volume levels.