I run a bak pak 2R on my tank and I am satisfied with it. I wouldnt say very satisfied, but it does the job.
Pros:
Cost . . . mine was brand new for 110, 150 shipped to my door with the preskimmer, bubbletrap combo.
Size . . . IMO its a relatively small skimmer that does a pretty effective job with the space its got.
Output . . . on my tank, it pulls out some pretty thick green foam and I empty my cup about once a week.
Cleaning . . . it takes me less than 5 minutes once a week to clean the collection cup. Once a month, about an hours worth of time to make the thing look brand new.
Cons:
Noise . . . I can't tell when its running because I am used to it, but when you turn it off its noticeably quieter.
Break-In . . . . it took about three months for this thing to finally stop putting bubbles in the tank, even with the bubble trap. At first, it put the bubbles in non stop, it did that for about a month. Then it only put bubbles in when I fed the tank, finally after about two months of that it stopped comletely and I have never seen another bubble since that came from the skimmer.
Fine tuning . . . this skimmer takes a LOT of fine tuning to get it to function at its best. I mean a LOT. Sure it will work stratight out of the box, but to really get it to function at its optimum level you really have to play with it. However, once I got it "tuned", I have never touched it since.
Neutral comments:
The pump . . . it comes with a rio 600 RVT. I know that a ton of people out there bash rio's to death and refuse to use them. I am not one of those people. I think that the people who have their rios break on them dont take care of them. I have run my bak pak with the original rio for well over a year now and it has never quit on me once, nor has its performance declined in almost two years of use. It simply requires the monthly cleaning as described above and in the users manual. However on the contrary, when the rio does die I will switch to the maxi jet 900 for the sole reason that I dont think that the rio keeps up with my bio load now.
Tank size . . . CPR claims up to 60 gallons. NO CHANCE. I would never put this skimmer on anything over 30 gallons. But under 30 gallons, this is IMO the better if not the best, HOB skimmer available.