I have a Tempest, Davis and Ambient WS5000.
The Tempest is a cool design, but IMO has 4 problems which take it off my recommendation list.
1. Rainfall estimator (Rain gauge) is unreliable. Does not catch very light rain and in general is way off on rainfall totals. They have a new feature called NR (neighborhood rain) where they will "correct" the rainfall estimates to what shows up in other weather stations in your area, including COCORAHS reports. That is nice but if you really want to know what happened at your house, that may not work for you.
2. Depending on site placement, unit will lose charge (over the course of several weeks) if it does not receive DIRECT sunshine for a few hours a day... at least a few days a week. i.e. even here in Atlanta with shaded areas in the fall (when sun gets lower)... it will not charge and could eventually shutdown. They are working on supplemental power source options because of this problem.
3. Wind is sampled once every 3 seconds missing short lived wind gusts. Not an issue if you are not in a gusty area... i.e. open exposure on all sides, lakeside, open fields, etc... My Ambient WS5000 does a much better job of catching wind gusts than the Tempest.
4. Water droplets hanging off of the upper part of the unit will sometimes cause erroneous high wind readings. I think they may have addressed this with software because I have not seen it lately but perhaps that is also why it misses some wind gusts mentioned in #3 above (not sure).
Hope that helps.
George