I used to have the waid e angle wetmate and didn't like it at all. It was mated to a 995 so that might be it but the edges were not very sharp.
Curious, I didn't think Light & Motion ever made a Tetra for Coolpix 99x cameras. Are you talking about the same Tetra Wetmate lens? Even if LMI did, you're comparing apples to oranges because the Coolpix 99x is an entirely different camera from the Coolpix 5000.
wrt cost, yes the wetmate is more than the Nikon. but what isn't with underwater gear? the WC-E68 is not actually < $100. It lists for $179 and B&H has it for $139 plus you have to buy the adapter. There's like 4 times the amount of glass in the Wetmate lens compared to the Nikon and I have hundreds of examples of sharp corner to corner wide angle images I've shot in the last year.
wrt ROC, I use dual DS125's and have found in brighter waters the TTL works ok (not 100%), in the darker waters here in the northwest, not so good. The ROC is awesome and I use it ALL the time. I'm going to miss it when I get my housed DSLR next year 