I have a Baader one that works quite well except there is still a bit of play in the focuser locking ring so getting a repeatable position each time you insert the laser can be a bit tricky and I now use star colimation if I want to be really accurate. I recently heard of these self-centering colimators - sounds like a really good idea but I haven't tried one yet.
http://www.myastroshop.com.au/produc...sp?id=MAS-280C