Maggie owners (past, present, future) what do (did) you love and or dislike about them?

1+ richopp. I would like to add that the 3.7i might have the best cost to performance ratio in the industry.

I know that these discussions can sometimes get testy, well, I am not here to do that but.  Maggies are the best speakers that I personally have ever heard.  I have always wanted to listen  to a pair of ESL's , but have never had the chance.  I owned and listened to a Pair of MG-IIBs for more than twenty years, only changing when I moved into a new house where there just was not enough room for them.  I was going to sell them, but never put them up for sell --still hoping that one day I can use them again. They were powered by an Audire amp rated at 100W/ch at 8 ohms, and 150W/ch at 4 ohms.  The MG-IIBs offered a purely resistive load of 6 ohms -- no complex impedance to strain your amp.  You just need a well built amp, capable of putting out ample current. I know that many will say that times have changed and the current models are better and I hope that they are, but the only thing that those speakers ever needed was space, power and a little more base - with the right amp, only a little more base.  I once auditioned a pair of Vandersteen 2Ce speakers because I had heard how good they were and walked away, unable to give up the clarity of the mid-range and upper base that the MG-IIBs offered. By the way these guys are built like battle ships, no problem with anything.  The dealer pushed one over once onto a concrete floor and it wasn't hurt, just to prove the point.

I have had multiple Maggies over the years, SMGa, .6, MG-12, 2.7, currently 3.5s with Mye Stands rebuilt by Magnepan last year.  I have also had many dynamic speakers, Celestion 15, NHT SB-2, Vandersteen 2c, Vandersteen 3A Sig, currently Totem Mites on my desktop.  My observations relative to your questions:

1)  Maggies have compromises, as do all speakers, depending on the persons, the benefits of Maggies outweigh the downsides.  People seem to either love them or wonder what the fuss is about.  

2)  Your room is large enough.  I ran a set of 2.7s in a 14x17 foot room for years and they were wonderful.  You should treat the room, GIK acoustics is a great source of help and reasonably priced treatments.  

3)  You amp has enough power, barely.  The larger Maggies want more power.  I found with my SMGa's, .6, and MG-12s, about 200w a side (into 4 ohms) got the job done.  The larger maggies really like 500w/ch a side or more.  You might want to consider 1.7s if your sticking with your amp, you are what I would consider on the edge.  

4)  They are big.  The 3.7s will dominate your room.  

I have had 3 sets of Maggie's with 1.7i's the last.  I have struggled with setup for 4 years until quite by accident had to push them into the wall against windows that had two layers of heavy curtains. Somehow everything came into focus with all the details I had been looking for. A fluke or have I stumbled onto something?