I just bought the Eshopps PSK-100H last weekend from a LFS. Since this is my first skimmer ever, please take my comments with a grain of salt.
1. I like the fact that the pump hangs below the unit. Only 2 tubes in the DT so it looks nice and clean.
2. The HOB skimmers do NOT come with an air silencer. It's louder than I wanted it to be. I called the LFS where I bought it and they were nice enough to give me a silencer from an old in-sump unit. Now it's nice and quiet. Eshopps wouldn't even respond to my e-mail with a solution except to say that the new HOB models simply don't come with the silencer.
3. I couldn't get the bubbles in the collection cup to go up high enough to create any skimmate at all. Then my wife peeled off the protective backing on top of the collection cup to reveal some air holes on top. Doh! Suddenly the adjustment valve works like a charm and it's skimming its heart out.
4. The micro-bubbles in the tank are excessive. Still early, but I can already see improvement. I have a feeling the bubbles will be gone soon. The Eshopps website and instructions say to allow 72 hours for a break-in period. I'm thinking the reality may be closer to 1-2 weeks. Then again, maybe the period is longer for me because I barely have any bio-load in my tank.
I have no idea whether a different HOB skimmer would do a better job, run quieter, with less bubbles, but overall, I think I'm going to be happy with my unit soon. Much is left to be desired in the instructions and customer service.