I use a deep socket still instead of that combo wrench...I will probably upgrade one day, but I already had the socket set and it worked fine for me.
As far as the stuck star shaped post, I had the exact same thing happen the first time I took apart my "new" keg two weeks ago. I had to apply a LOT of force to get it to start turning. I was really worried it was broken or I was doing something wrong, but after checking around I kept at it. What actually worked in the end was tapping the socket handle with a rubber mallet. Even better, if you have it (I didn't) is to slide a length of metal pipe/tube over the end of the wrench, effectively lengtherning the handle. You can achieve ridiculous levels of torque doing that. That was the trick some guys showed me. They used that method to tighten up big ass lag bolts when installing deck railing. Mechanical advantage, for the win.
