IMO, not worth it. If you need MTB tires, then do check out the BG, and I've heard good things about Thorn. I've seen a few (never ridden one), it looks like an awesome beast of burden.

My sister (same size as me, 5'2") hates her Atlantis - it doesn't handle right. She's taken it back to Riv. for them to check the geometry, they say there's nothing wrong, but it's unstable. She will probably sell it and buy a 520 for her next tour (if there is a next tour - she doesn't like touring that much.) Problem is, it's a lot of money for a bike you can't test ride.

Who said the 520 is flimsy? I like my 520 a lot. I only ride a little gravel, though, so the tire size might be an issue. There is clearance for a cyclo cross tire. If it's not an issue the 520 is a whole lotta bike for the $ (swap cranks for MTB cranks, though).