I'm not that impressed.
An 850 ft tower puts the antenna more than high enough for it to be a line-of-sight connection at 18 miles. 50 mW at 18 miles gives about -104 dBm of signal with 0 dB antenna gains in free space. It is probably more like -101 dBm since the signal is not radiated spherically. Adding in a little antenna gain could make the signal about 95 dBm. I have a $5 ISM band regenerative receiver with a specified sensitivity of -103 dBm. It won't do 3.7 Mbits/sec, however.
It sounds like it might be good technology, but not a miracle.
Cheers, John