One of my co-workers just installed a Pack Rat rack and 1550's.. Very nice set up.. He also put a 1450 on as a top box.
I used to use a Garmin Quest, but my only issue was that it has a very limited amount of memory. 115mb, if I'm not mistaken. I had a solid, powered mount on my old Wing, and I let the GPS go with it.
I bought a Garmin 2610 and a 2gb Compact Flash card, and now have US and Canada loaded completely, with room to spare.
The 2610 was discountinued a year ago (because it doesn't have a MP3 player and Blue Tooth, like I cared) and originally sold for $800. I bought mine a month ago for $160, new in the box.
The downfall of the 2610 is that it's not battery powered, so you have to run juice to it when using, but since the KLR's have a spare, unused, switched, fused power connection in the fairing, I spent 10 minutes to wire it.
It's a bit bigger than the Quest was, and it's bigger than the Zumo, but it's waterproof and like I said, I have EVERYTHING loaded on it.. Not a big deal on the KLR, but I swap it back and forth with the new Wing, and wanted the freedom of not having to download maps on a regular basis..
Here's a couple pics of the new GPS. Mounts are all RAM mount equipment.