Quoted from gecko157:Go with the pro. The flow is so much better on the pro. You can mod it to add more lights. Go back and read the old Metallica owners thread, the hammer is a problem.
If I remember correctly from my research,it was a problem with the magnet board. Hopefully the games produced after the problem was discovered are okay. And the older games should be okay once the board is replaced. I'm not sure if there are anymore problems with the hammer,but I'll be following this thread to find out.