dbjerke
n3wb
900's would have better vegetation penetration as long as its not extremely dense, as higher frequency has better bandwidth but lower vegetation penetration and lower the frequency, lower bandwidth but better penetration....but they'd likely be older, removed-from-service radios.
I'd perform a site survey and see what the noise floor is, if not a lot of ambient 2.4 GHz I'd try that using a higher power/higher sensitivity radio like the Nanostation M2 which is rated 23 dB minimum. BTW, just saw them in stock at Ubiquiti for $89 which will NOT last long if it is, in fact, in stock and at that price.
From experience what kind of distance would you expect out of the Nanostation M2? And do you need to pay for a monthly subscription with Ubiquity for those as well?