I run two 2002s and two 2004s on my 120G tank. The 2002s are in the back rear corners and the 2004s in front corners, all pointing diagonally at opposite corners. The streams are in my basement, one on my growout 100G tank and the other on my fuge/sump 150G rubbermaid tank, both running on the 7094 controller that used to run the main tank.
I originally purchased them for precisely the same reason you mentioned, having as little machinery in the tank as possible. This was also pre-stream days (2002.) I never considered the closed loop option at the time but I do think closed loop can be a good option for the front returns if you have the space etc. As Roger will attest, this is OLD technology, but the pumps apparently still sell well enough to warrant keeping them in production. Personally I still love them and I had a stream in the tank for a while but just found it to be too big and intrusive. That said, I might still add one in addition to the classics because my tank is getting really overgrown and the additional flow may be needed. The pumps are not without their drawbacks. Roger will tell you they need bearing replacements every 3-4 years I think. I take each of them apart every 6 months or so to replace some plastic components in the drive shaft ($12 parts) because salt creeps up the inside of the drive shaft and destroys these pieces. They get noisier over time when the salt is doing its damage. Also, since they are air cooled you can hear them. And, depending I guess on the tank, stand, and floor you can also get some resonance from them that you can hear like a hum. This may be particular to my setup on a hardwood floors that are not solid underneath.
None of which bothers me as they're in an enclosed hood. Also, while you may never have to take a stream completely apart, I have to work on my stream's impellors for calcium buildup more often than the classics.
Finally, as Roger mentioned, you need the pump adaptor to run the pump on the controller. You can run more than one pump off of each adaptor, but by doing that you can't have 4 independantly controlled pumps on the 7095 if you only have say two pump adaptors. You need one adaptor for each pump if you want separate control of each pump. So there's additional cost. That said, for my application I'd never need 4 separate controls, just two settings for two pumps running on each adaptor. Hope this helps!
