Pure Class A shootout

Hi after doing a lot of research and listening, I think pure class A is still the way to go for me. I'm wondering if you have any opinions on the following amps and how they compare with each other:

1) Gryphon Colliseum (mono or stereo)
2) Gryphon Antileon Signature (mono or stereo)
3) Pass XA 160.5 or XA 200.5
4) Krell Evo 2

They will be powering Rockport Altair's or maybe Rockport Arrakis (still debating that one too).

I see a few dilemmas. For Krell, it seems like the spirit behind their products Dan D'Agostino is no longer with the firm and thus maybe their brand/lineup in the future may be compromised. Also, Krell's preamp reputation is not as good as their amplification. That's similar to Pass as well - great reputation on the amps but not as reputable on the pre-amps. Don't get offended as I'm only talking relative terms (i.e comparing products at very very lofty levels). For Gryphon, their amp and preamps are supposedly top notch, but right now the Euro is extremely strong vs the US$ and I'm thinking I should be picking up something American as it's more of a bargain. Gryphon + Rockport is a "formula" and I know I can't go wrong with it but I'm wondering if there are other options.

So I guess the question is:
1) Have anyone ever compared the best Pure Class A amps? How do they compare with one another? Yes I know they are all good at this level but unfortunately I have only listened to the Gryphons mated with Rockports.
2) Any other options that I should consider? No tubes please as I have no desire to mess with tubes.
3) Should I even compare/consider the older pure class A amps like the ML 33/33H? i.e are the new pure Class A leaps and bounds better than the older reference lines?

Thanks, -Isaac