People either love or hate the Remoras, it seems. They seem to work for some, not so good for others. For me, it's hard to nail down the problems because everyone's tanks are so different. I do know that the quality has gone downhill since I bought mine 3+ years ago. I bought a new collection cup within the last year, and it's obviously made waaaay cheaper than the original one. The tube is glued in crooked, rough edges on the inside, etc. Really disappointed, but it still works fine.
There are definitely more powerful skimmers out there, no arguments there. But you really can't beat the simplicity and plug'n'play aspect of the Remora. There is just absolutely nothing adjust or futz with. (And I think that's what some folks don't like about it!)
Regarding your skimmate... I wouldn't expect it to get really dark. Here's a shot of what my "normal" skimmate looks like. My bioload is not super heavy (1 clown, 1 cardinal, 1 tiny goby, 3 chromis in a 46g).