Jasone, I got a FX3 recently, and have only used it on one trip for turkeys. I haven't seen or used a 500, but am very happy with the FX3. I wouldn't spend the extra money on the 500, but would invest it in the SP-8 speaker for the big animal calls. The FX3 remote will control the Foxpro Jack-in-the-box also. I agree with Car-ver, it seems like the decoy could seal the deal on a wary predator.
I am also impressed with Foxpro's customer service. I like that they are made in America, too.
Wade, good looking pair of retired fawn killers.
Good hunting, Tom