Stay tuned, I may be testing the FoxTech goggles shortly as well.
If you want to fly around obstructions then you'll be better off with a lower frequency than 5.8GHz because, as you go up in frequency, the signal begins to act more like light -- being absorbed by most elements of the environment (such as trees and hills).
900MHz should be the best but (and this is a *BIG* "but"), there are very few places where you can use 900MHz without a HAM radio license - or at all. The same goes with 1.3GHz - it's also not without problems.
The key to long-range with 5.8GHz is getting your receiver antenna as high as possible. I obtain 2Kms of range because mine is perched atop a 3m pole. I tuned my receiver to a friend's FPV model this weekend while he flew with a set of goggles that have a built-in 5.8GHz receiver and he was losing the signal at 400-500m of range while it was still absolutely clear on my setup -- simply because my receiver was atop the pole.
I'm working on a full comparison of the various frequency and power options for FPV and that'll include their ability to cope with obstacles between the model and the receiver as well as how to best set them up.
Remember though -- your RC system is 2.4GHz so if you use a lower frequency for your video, you may simply get to watch the plane crash as you lose control - because the RC signal is blocked by something that doesn't block the video.
RCModelReviews.com, just the facts.