I lost all mine in the move...and am desperate to get some more; going to pick up a cleaning crew this afternoon and hope to get the lfs to toss in a few. I had 4 10-inchers I grew quite fond of, minded their own business and did their job very well.
I'd hate to try to run a tank without them.
If you're growing algae, it's a sign of health, but it's a lot better if you can put a refugium somewhere into the loop. I've only run one for a week, and I'm impressed at what I see going on.