We used an eveluation kit from itran in the early development stages which is what convinced us that we needed to develop our own asic but the eval kits do give you an idea of what to expect in terms of performance.
We eventualy ended up with a system where the meters at houses would send data on a weekly basis to the local substation,from there the data was compressed,encrypted and sent by modem to the power company.This was the only reliable way we found to get over some of the more difficult problems.
I think that you will find is that there isnt a real solution to the problem of transmiting data over distances much more than a couple of miles.You are using comms systems which are really designed to overcome deliberate jamming by impulsive noise and they still do not operate reliably.