I have one of the 5.8ghz Nikkai ones. They are good but not HD the 5.8 ghz signal means your wireless internet does not interfere. They only connect on a scart lead though. You also need a clear sight from sender to receiver or the picture is distored. I have my front room sky box connected through to my conservatory. It will go through the glass doors but struggles when ppl walk past the signal or you have objects like chairs etc in the way. OK for £69.99 but would love something that is true HD replication. I am not so desperate to spend £700 on it though!
I like many here had become frustrated with my phillips 2.4ghz sender and purchased a new QOSE 5.8 ghz sender on amazon. I am pleased to report it works brilliantly on my sky hd box, and sends a perfect picture to the bedroom 30 metres away through several walls and one floor. The remote function also works well, and the best thing for me worked first time out of the box no messing with aerials or fiddling with the channels. The picture isnt HD though, dont think it is possible