Magnepan upgrade

Eminents are great, see if you got a dealer near you. Or call Bruce at Eminent Technology to see if you can get a home trial. I have owned the Eminents for 12 years now and no itch to upgrade to something more expensive, cause that would cost a lot.

Buy Sound Lab Electrostatics and you will get what you are seeking. You can get off the component-go-round. They are a line source single membrane electrostatic that is covered by various patents. Now they have the 545 series that stands 5 feet tall by 25 inches wide. They offer versions that go up to 9' and more on a custom custom basis.

I've never heard the Eminent Technology LFT-8b planar.
I agree with zavato's first part of his statement, assuming your room is large enough that you can correctly set up a pair of Maggies regardless of their model number. I would also add to that and say if you don't already own a pair of Mye Stands you really need to purchase them to hear what the Maggies are capable of.

@ OP,
Those 3.7's are awful big, but I bet they will sound amazing. I think Zavato's comment worthwhile- maybe adding a sub(s) would give you much of what the 3.7's can do. If I recall, more than half of the planar speaker is needed for bass reproduction, so the much larger 3.7's will move more air than your 1.7's.
B

The OP has to listen the the two Maggie's side by side. I suspect that the 3.7i's will do just about everything better but you may also come away thinking just how good the 1.7's are. I knew someone that considered going to the bigger Maggie's and wound up adding a subwoofer instead. 

Do you know about the Eminent Technology LFT-8b? Some listeners prefer it to both the 1.7i and 3.7i. It, like the Maggies, is a magnetic-planar (from 180Hz to 10k), with a ribbon tweeter and dynamic woofer. $2499, a few hundred for the almost-mandatory Sound Anchor stands.