wireless T1 connection to ISP

Hello.
We were recently approached by a local ISP to convert our current T1
lines to a wireless ethernet connection and save money. We have around 30
users in the building and host 3 websites, smtp, pop, etc. I would like to
keep our bandwidth at 2 T1's (3Mb). We are about 1/2 mile from their tower.
We do not have direct line-of-sight but their tech came in and measured the
signal strength and assured us that we can get the bandwidth we need using a
Tsunami Quickbridge 11 operating at 2.4GHz unlicensed spectrum.
I know nothing about the reliability of these connections. I am happy
with my current setup but would like to switch if the performance is the
same and I can save money.
What do you guys recommend. Could somebody point me to some articles
where I could read up on the reliability of this equipment?? Also we are
located in the North-East.. are these things weather-proof?? Is bad weather
going to affect our connection??

Thanks in advance.

Sanjay Patel