Mykesinger,
I have the 2.7s and like them a lot. I bought them used 3 years ago through Audiogon and they're still going strong. I did compare them to the newer 1.6s and the 2.7s were definitely better in my opinion: fuller bandwith, deeper bass and more natural tonally. The 1.6s may not have been fully broken in but if Magnepan still offered the 2.7s they would be more expensive than the 1.6s. 2.7s are 3-way and 1.6s are 2-way speakers, both with internal crossovers. Also, they both use a quasi-ribbon, not the true ribbon like the 3.6s.
They do seem to need lots of power. I'm driving them with an Aragon 4004 (400 watts into the 4 ohm speaker load)coupled with a tubed preamp so your amps are plenty. Was thinking of trying a Classe amp myself. Haven't done any upgrades but am interested in possibilities as well. I don't think you'll be disappointed with these speakers. They hold their value well and you don't see too many pairs listed for sale, which tells you something. See ya.