As might be expected, the Fet Valve stuff will sound better than the Omega stuff which sounded better than the MosFET stuff. I've had all three and that's my experience.
About a year ago I moved from France to the US and found myself with complete Omega (wired for 240) and MosFET (wired for 115) based systems. (The MosFET stuff sat in my attic for 10 years, along with a broken set of magnepan tympanis.) I was also in a position to set up a HT room in addition to my regular listening room.
I upgraded all the Omega to T-7/FV 350 (and Ultra DAC) for my main system and kept the MosFET for the HT (which houses the tympanis as well). In other words, I put the best I could afford in the main system. However, the MosFET is NOT the weakest link in the HT - it's the signal from my stinking cable company.
The Omega is great stuff, and is one of the better - if not the best - solid state designs out there.