The only problem I've had using the floodlight motion sensors with my pneumatic props is that they cause a great deal of ghost trigger of the prop. In other words, when triggered, it'll cause the prop to continue triggering numerous times up to sometimes 8x before resetting. I've tried using that relay fix that was on someone's website, but it didn't solve the problem. I'm wondering if trying a different floodlight brand would help. Aside from that, those motions sensors are excellent.
As a part-time electrician, I try to avoid the cheap motion detectors. They can be WAY too sensitive for most applications. Even when you buy the narrowest beam possible (around 110*, I think), they trigger at the most inopportune times. I had one on my garage that the bushes on either side would trigger when even a slight breeze set them in motion. A heavy rain would also set it off. I finally eliminated the problem by buying a more expensive detector from an electrical supply house instead of a home center. MUCH more adjustable and long-lasting. End of problem(s).