I know the flash spooks deer. I was sitting in my stand before daylight one morning. I buck walked up to a nearby scrape where I had my camera. When the flash went off, he jumped in the air and then hurried off.
I bought a Moultrie I-40 last year and have been very pleased with it. The battery life is unbelievable. Even with the IR camera, I've noticed the deer are always looking when the shot is taken. It may be noise or it may be the IR flash, I don't know. Either way, it's better than the flash camera. I've turned off the flash on my non-IR cameras since seeing how they react.