In terms of raw horsepower and size of the bike, no problem.
In 2010 I spent 3 weeks riding in the Rocky Mountains and crossed 13 passes at higher than 10,000 ft in elevation. The only problem I had with my DR650 (not a typo - I was on the big Suzuki thumper) was with it running rich due to being on a carbureted bike.
So I would say go for a later model DL that is fuel injected, that way the O2 sensors in the system deal with the oxygen supply in the atmosphere.
Current rides: 2001 GL1800, 2014 DL650 Adventure; Gone away: 5 BMW's, 4 Honda's, 2 Suzuki's
"The object of life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane." -Marcus Aurelius