Just finished shopping for a new GPS. I had it narrowed down to the Quest and the GPSMMAP 60C.
I ended up going with the GPSMAP- two reasons- over $100 dollars cheaper, though the Quest does include software that can be pricey if purchased seperately, but I already had it. I also prefer the "handheld" format, seems a bit more rugged, but that probably just me.
115 mb is plenty. Hell, GPSMAP only has 56, and I think that's is plenty. Only time I could see needing more is a multi-week trip on all backroads. Remember, you get all state and U.S. routes, highways, tollways and such without using a single mb of memory. You only need to load areas where you'll need residential and business level streets. I've been doing fine with only 24mb for the last couple years.
Example- my mapset for the Mega meet. I could have easily left off everything between my house and Arkansas, I'll be on at least state level roads the whole way. Only reason I bothered is I have the room. That's a touch under 53mb...
These guys are a great place to shop/compare- www.gpsnow.com . I've found two places that are marginally cheaper, but gpsnow.com has great customer service and well defined shipping policies, which I like.