I did use a CL {Dart and OM}, but i feel that there are some downsides, at least in my opinion.
I have since dismantled the CL, since i used over-the-top style plumbing, i am now using Tunze Streams.
Here are the downsides i found
1). My suction from the Dart CL, killed several fish including a special mandarine fish, which was eating pellets and frozen brine shimp, and a Copperbanded Butterfly Fish
2). The suction/water flow pipes under water would constantly, need cleanings.......ANNOYING
3). The watts on the Dart were prolly double what i am pulling now and i was pushing less water
4). Although the flow alternated it was NOT random by any means. Tunze streams do this much better IMO, with the Multicontoller, of course
5). The plumbing apparatus was ugly.... i guess so are tunze streams, but they are easier to clean and somewhat hide.
6). With CL pumps you have constant maintenance issues, like impellar cleaning, which means dismantling pumps and pipes in awkward speace, behind the tank.
7). The Oceans Motions 4 way was horrible to dismantle for the above reasons, and the fact that when it did gum up (due to Calcium, Alk, and Magnessium deposits) it was a bear IMO Twice in 6 months.
8). I really don't want anymore unnecessary holes drilled in my tank, they are failure points and prone to salt and water creep.
So for my needs the Streams were the choice for me.
Hope it helps