We put four of them in our LMB pond, jdfish.
First, a quick word of caution: If you are setting them in cement (we used 5 gallon buckets to set them), make sure you do it at the pondsite. Transporting the fragile PVC, especially in the back of a pickup, is quite a chore.
As for effectiveness...the jury is still out.
I didn't catch anything off of them for the first 6 months or so. I snagged a few lures on it, though. They're much better about that than other structure, but they aren't snag-proof.
Recently, my dad and I both have caught a few LMB off of them, so that is a good sign. Hopefully they will continue to be productive.
