CAT SL-1 questions

I've been researching these pres and I have three basic questions-
1. Whats the diff between SL1 Mk1, 2, 3 and SL-1 Signature.
I know that the SL1 Mk1 had a rep for eating tubes, which suppossedly was tamed in the MK2 and 3. Is a SL1 MK2 more desirable than a Signature MK1?, etc.
2. Does the phono stage of an SL1 or an SL1 Sig have enough gain for a Benz Glider low output (0.3 mv)?
3. Anyone ever use them with McCormack DNA 0.5 Rev B or Rev A?

Thanks for your help.
I'll try to answer some of the questions: The Signature has even less noise than the previous models. The Ultimate has a better sounding phono than the Signature. The line from the 3 onwards is very good IMO, with dynamics and musicality winning over analysis.
Some of the changes are due to using different tube biasing and manufacturer of tubes...
The phono is quite flexible with loading and should drive your Benz. I used the Ultimate phono on a Clearaudio Accurate w/out difficulty.
I take one(used) to audition this weekend and I'll tell more. Folks say that the phono section in CAT preamp is superior to ARC PH3 and if it's realy true(i have one to compare with) than I keep the unit if it's not, well, I'll just kick it back.

Dealer told me that the input sencitivity of the phono section is 0.5mV. If the specification sais so I wouldn't try to go lower. Even the lack of .2mV can reduce dynamics significantly especially in Benz Glider.

McCormack amps bring more colours than you can only imagine to drive the sound away from real music, so I bet you won't be able to grade properly $6000 preamp IMO.
I once owned the SL1MkII. Wonderful pre. I also had the opportunity to hear the Ultimate and found that I liked the Mk II better... warmer. Whereas the Ultimate tends to sound drier VERY detailed. Remember this is relative to the CAT sound. I would not go any lower in your cartridge output. To get a life like sound with my low output(Spectral) I had to turn the volume to the 3oclock position. Systems will vary. Frankly I felt the ARC PH3 was equal but had higher gain than the CAT. You must hear for yourself. Both Pre's are top shelf. If I ever get back into a tube front end the CAT is still my favorite. The best bang for the buck is the MKII or III.