Anyone use Grappling Dummy?

I was wondering if anyone uses a grappling dummy. What is their experience and if they are worth the investment??

I have a BubbaDummy and it's great.  It doesn't take the place of training with a live resisting opponent, but it's a great tool to supplement your training.  You can also practice striking and cranking your submissions.  The evil genius who invented the BubbaDummy posts on this site.  I haven't used other training dummies, but I did a lot of research and believe Bubba is the best, even if it does have a little bit of an attitude once in awhile. 

Gary Hughes