I have a Gen-X PCX-40 on my 90 for my closed loop. I don't have a lot of experience with external pumps (in fact I would say none), but it did seem a bit loud at first (it's in a cabinet next to my tank). I did two things that I think cut down on the noise a lot. First, I cut up a beer coozy and made a little stand with pieces of it tucked between any parts that could move to cut down on the vibrations. Second, I lined the inside of the cabinet with a bed pad (the egg crate looking stuff) to help absorb the noise generated by it. These two things made a huge difference. I have two big computer fans in my hood that run with the lights, and with the modifications I made around the pump, they definitely drown out the sound of it during the day. You're welcome to come have a look/listen if you like.
As far as dependability, I've had it for only about 9 months probably, but it's been running pretty much non-stop for that long (cleaned once, but probably didn't need it). I never had a problem with it starting back up or anything like that. When I was looking into it, Fishboy said he had a few and they have all lasted a long time/been dependable. Of course, he doesn't have to worry about noise as much as people putting them in their living room.