The XM29 may not be as rare to come across as the Megaview, but I would argue that it is likely the more desirable monitor. From what I've seen, not only is it a bit easier to work with when it comes to configuring it, it's also more easily accepting of different signals the the 3730c. I've has it since August or September and I've only just in the past month or two gotten it to "properly" display higher quality signals.
To put it a bit more plainly, RGBS and RGsB have been done properly; RGBHV is doable, but only thanks to a terribly thrown together HD15 to DB15 cable, which ends up causing quite a lot of interference in the picture. With the NEC, it would have been literally as simple as grabbing any standard VGA cable and going from there.
This is by no means the norm, but I managed to get mine for little more than a few sore backs and a very odd conversation in transporting it across the city.
My camera is rather shit for capturing video, but I think this came out decent enough. The Megaview is being fed RGB and the other two are composite: