The 8-ch duel conversion RX is probibly fine. I don't know how big or heavy it is, and I don't know who services it though. RX's take a beating in RC Combat, and it's nice to have somewhere you can sent it when it breaks. (not so much "if" as "when").

The small, single conversion GWS RX, I wouldn't use in a combat plane. I have one in a park flyer, and I get hits all the time, usually when other transmitters are on. It has great range when I'm flying by myself, but get a couple other TX's on in the wrong combination, and it's "hit city". It just does't toss out the intermodulation effects very well. At a competition, you'll have many TX's on at the same time, in very close proximity. I doubt the GWS single conversion RX's are up to the job. Not that there aren't single conversion RX's out there that are ok, but I'd be careful with such a cheap RX.

Also, in my expereince, caseless RX's have a much higher failure rate than RX's that have a plastic case. Many other guys use caseless RX's with out problems, but I've been phasing mine out in favor of RX's that have a protective case.