I may be a little late to the game to add any meaningful advice, but incase You haven't made a decision yet.....
Regarding the Quads and the Maggies, I, over the years, have owned and immensely enjoyed both. For 20 years I had as my primary speakers in three different homes a pair of Quad ESL 63s. Along with these speakers, I was continually trying other speakers. By comparison, I found that the earlier Magnapans sounded a bit thin and nearly every box speaker, compared with the Quads, lacked the breath taking realness through the vocals and mids. The Quad ESL actually favor a slightly bright wall behind them. In their first home, there was a very large window behind covered only with light sheer drapes and were about 36" from the wall behind and a little over 2' from the side walls. They sounded incredible. I only sold in Lue of a small set of dynamic speakers when work moved me into a much smaller living environment.
I have been disillusioned by the new Quads, both by their manufacturing being moved to China and by their horrid record of reliability. My old ESL 63s had served without fail or fault for 20+ years and were still going strong when I sold them. A good or re-furbished pair of the Quad ESL 63s may be a good choice.
Now retired and back into a larger home (listening room approx. 14'Wx27'L and 10'H) I decided to try a pair of the newer Maggie 1.7s and fell in love. Unlike the early Maggies that, to me, sounded a bit thin, the new .7 Quasi Ribbon models (.7. 1.7i, 3.7i) sound not only detailed with a large stage, but also sound full and musically engaging.
My 1.7s are about 46" from the wall behind, but you could get by with 3' as long as you have a set of heavy drapes that can be pulled across your large window, when listening and a carpet or throw rug in front of ea. speaker. They do require a bit of experimenting with distance apart and toe in but when finally getting their set up tweaked, I don't believe there is anything at anywhere near their respective cost, that is as musically. engaging....Jim