I have the Sigma BC1609 wireless cadence on my roadbike and I love it. Start up takes a couple of seconds and thats about it. No other issues at all so far.

Just picked up a Sigma BC509 wired computer for my hybrid today from Performance for $8. Haven't been able to test it out yet, been raining all day. I do prefer the look of the Sigmas over the Cateyes. Plus they are a better bang for the buck.