distortion won't be visible in many if any climbing photos, and only in photos in general if you've got dead flat straight things like buildings or a horizon at sea for reference. so its probably less of a problem than you think. if its low-order distortion it should be pretty easy to correct in any normal software. most zoom lenses have distortion to some degree.
what i'd quite like now is something small that i could use with 2 or 3 pocket wizards and small flash heads to do some camelback-portable biking pictures. my current and fairly impractical setup consists of the d200 and a very heavy norman 200b system, which really necessitates the employment of a chinook and crew to deliver it into position.