My replacement U2 has 4 over the 3 of the original. The switch has worked fine for some time. I did have to adjust the tabs once after mating the tailcap to other lights. Since then, its been dedicated to the U2 with no problems.
I sent my U2 in for RMA due to a bad tail switch. This was in December 2005. It came back near the end of January 2006. The switch that came in the replacement has three tabs. It has been working perfectly.