What are some of the downsides of owning a Magneplanar .7 or 1.7i ?

I will second the vote for Spatial, especially if you have room or power concerns. I currently power a pair of M3 Turbo S with a first watt J2 (13 watt at 4ohm) and am quite pleased with the combo.

Hi sunnyjim

I don't have anything to add about the Magnepan 1.7i's, but if you are even considering them, this is what is on their website, today:

We’ll pay you CASH to hear the Magneplanar 1.7i
That’s right!
Not only will we pay the freight both ways, but we’ll pay you $100 for your trouble if you are not impressed and want to return our Magneplanar 1.7is after a 30 day home trial. (We are that confident that you will want to keep them.)
Millions of consumers live too far from a Magnepan dealer to hear for themselves why they might want to own a full-range ribbon speaker. Now, we and the dealer are making an offer to these customers to bring the speakers to their homes.
This program is intended to encourage dealers to reach out to nearby markets or states where we have no dealers. The financial risk is too great for a dealer, so we are lowering their risk by offering to take back the 1.7is if necessary.
We and the dealer must both agree that 1.7is would be the right speakers for you (adequate amplifier, room size, etc.). We will ship the speakers directly to your continental USA location. The paperwork will be handled by the USA Magnepan dealer nearest you. The dealer and Magnepan incur certain costs and risks with this program. We and the dealer reserve the right to decline this offer if, in our judgment, the 1.7is are not the right model for your installation or you live near enough to the dealer for an in-store demonstration. First, call Magnepan and we will explain this program in more detail and determine if the 1.7is could work for you.
Offer expires on July 1, 2017.

http://www.magnepan.com/model_17

If you take them up on this offer, please let us know what your final decision is.

Enjoy!

I've owned the MMG, 1.7i's, 3.7's, and 3.7i's and would say that Magnepans need a lot of room behind them to really reach their full potential.  I'd say a minimum of 5'--preferable more.

4 pairs I owned did their best square in the middle of the room.
As is common, I put tape on that spot and left them against wall when not playing .

"4 pairs I owned did their best square in the middle of the room. "

Of course if this is where you placed your speakers and found them to have the most satisfying sound that is just fine and of course very audiophile must decide for him/her self what qualities of their Music Reproduction System they find most essential and what characteristics they are willing to compromise in exchange for those preferred qualities. That said, placing just about any speaker but especially one with a dipolar radiation pattern such as Magneplanar "square in the middle" of a room is not consistent with their intended use and certainly not in compliance with their design objectives again especially with Magneplanars.

By putting your speakers "square in the middle" of the room you are getting essentially monophonic sound from your Music Reproduction System. Again this is fine if its' your preference but if your preference is for monophonic sound it would probably be a best course of action to use a single speaker with a single monophonic amplifier and keep everything in the Music Reproduction System monophonic all the way through.

With those speakers relying on a dipolar radiation pattern, placing the speakers square in the middle of the room you have essentially identical sound propagation both front and rear and when these waves meet at the ears of the listener they tend to cancel out. Of course this will not happen exactly that way because of subtle and slight variations in reflections within the room containing the Music Reproduction System but nevertheless the tendency is there an you are going to achieve a very uneven frequency response as a result of this very unusual practice of placing speakers square in the middle of the room.

Again I mean no disrespect to Mr. Shubert and his preferences in sound reproduction but this recommendation for placing speakers square in the middle of a room is most unusual and not likely to satisfy the majority of listeners.