Altar1,
People are dumping SA250mk4 amps because Plinius is in the process of upgrading their entire amp line. They started with the SA102, and the SA250 will be replaced I am sure as well. Plinius amps are great for driving Maggies. Maggies need and crave power. Plinius amps deliver it.
I think the GamuT D-200 is sonically superior to every one of your amps on your short list. I am selling mine to pay off some impending bills. However, I will replace it with a new D-200 in the future (watch for my review).
This being said about the GamuT D-200, I would NOT recommend buying a D-200 to drive Maggie 3.6's until you hear the results for yourself. The D-200 is a powerful amp; however, it really is not designed for speaker that are very difficult to drive. The 3.6's are on the very edge of what I would drive a D-200 with. HOWEVER, the GamuT might drive the Maggies very well... I would love to hear it tried. Why would I not try to drive the Maggies with the powerful D-200? The D-200 is designed to see a load less than 1.5 ohms as a short, and the circuit protection kicks in and the amp shuts down.
I know Maggie 3.6's dip pretty low in ohms in the bass (I think around 1.5 if I remember), so the D-200 would not be my first amp of choice when laying out a system on paper (without trying it first).
NOW if you have an active crossover from your subs to your Maggies (the subs getting everything below maybe 40hz), I would absolutely reccommend the GamuT D-200. The D-200 is amazingly detailed and transparent with neutrality that few solid state amps achieve (especially in the $8k and under price range).
KF