I remember selling the 717 back in the mid 90's and if I'm not mistaken its rated by Fisher @ 100w x 2 in stereo. I remember it out powering the Pioneers and Sony"s we sold! I sold one to my mother when it was on sale for $199. for her first H.T. set up and it's still running fine today.
Go with Wes on the wattage of the 717. I'm really not sure but 100W doesn't seem unreasonable. I know there was at least one model up in the lineup that was more powerful than the 616.
The 616 was not rated for 4 Ohm but I did run 6 Ohm Pioneer towers off of it for years. Don't know about the 717 but I would surprised if it was 4 Ohm rated.
Well, I built a 10" DVC Sub for my mother and had to run it on the front Left and Right channels so we were running the amp a 4 ohm and like I said it is still running great today. Load that baby up and drive it hard it's good for it!