Hey mate, how's it going with your maggies?
Just came across your post, and thought I might add some thought even though this is a late reply.
I've previously owned the MGIIIA, MG3.3, MG3.5, MG20 series. I found that positioning the panels with the tweeters on the inside gave a far more cohorent and focused soundstage. The owner's manual if I am correct also states to place the panels with the tweeters on the inside; however subject to change depending on the owner experimenting and room size.
With measurements what worked best was as follows:
4-5ft from the back wall, 5ft of distance between the panels measuring from the tweeter, and listening position 10ft. For maggies it was half the distance between the panels, compared to your listening position. Example, if your listening position is 12ft away, distance set between the panels should be 6ft, and so on...
For the side walls anywhere between 1-2ft was adequate, of course with slight toe in; again your owner's manual will suggest this. Moving the maggies is a real headache as they are big and sort of sway around, which could upset the ribbon element. Always move with caution in small increments.
These were my placement guidelines, and worked very well, untill of course I got my Quads, which is a whole different ball game.
Enjoy those maggies and remeber you will be moving them around for a while, one position never seems right with maggies. It also varies with music and across the entire frequency spectrum. If you've got their newer quasi ribbon designs this issue has been drastically corrected. The MG1.7 and 3.7 are great improvements over the previous designs.
Which one have you got?
Cheers, RJ