Quad or Magnepan?

From my experience selling maggies years ago and listening to a few Quads at Overture Audio in Delaware about two years ago, the 2905's specifically, I would go for the Maggies by far regardless of all other concerns if you have a good amp and room space as Quads need that too. The Quads seemed to have a homogenized sound that kept saying "SHHHHHH" as if they were telling me to stop talking. They sound like that ... cymbals especially. Shimmering is one thing, but they sounded that way much of the time overall. The dipole effect was severely noticeable as I got within about eight feet in front of them and is not as noticeable with the Maggies; be it with or without toe-in. Yes, I do thoroughly understand the physics of sound cancellation to the sides. Plus, the Maggies let you position the tweeters to the insides or outsides as you prefer or your room needs for tighter and better imaging or a wider soundstage. That option can also help them function better in your room due to size, wall and ceiling arrangements, etc. There is also good and valid reasons why Audio Research uses Maggies to test and voice their gear on for decades now. The Maggie is taller too, so it will naturally throw a higher soundstage, and does. I hope this helps you.

i find it interesting when a reference loudspeaker is kicked to the curb. i suspect you're bored.

These are such different speakers that I wonder how you narrowed it down to them?

At least as important as the speaker choice is your choice of amp to accompany the speakers. Maggies really do like a lot more watts, which gets expensive if you like tubed amps. Quads will flourish on moderate power tube amps. As said above, Maggies will sound realistic when cranked a bit, but below that threshold, they sound closed-in and dynamically constrained. I've had my Maggies for 10 years now, and love them to death. Occasionally, I've spent some serious time with Quads as well. They really are exceptional at retreiving low-level detail, and are great for late-night listening sessions where you don't wake up the neighbors.

Horses for courses.

If it were me, I'd also take a really hard look at Roger Sanders's electrostats (his new 10B's). They can really kick butt dynamically, and with the line-drive woofer will give you the gut-punch of solid bass that neither Maggies, nor Quads can deliver. At the same time, they are spectacular at detail and have the "breath of life." Roger wrote the book (literally!) on electrostats. Highly recommended!

Least we forget, the Mags also make excellent room dividers.