I'd like to pick up the Timney scar trigger for my 16, but I've read about light primer strikes.  Can I run the Timney 17 trigger in a 16?  Supposedly the only difference is a stronger hammer spring

This is not a direct answer to your question, but the Geissele Super Scar trigger doesn't differentiate between the 16 / 17.  If you haven't felt a Super Scar...you should before you buy the Tim.

I've got a few G triggers already (and another on the way after this weekend sale) but really would prefer a single stage trigger for the scar

Yes, you certainly can - as you indicated, the 17 model has a stronger spring for 308 ammo and 0.5lb heavier pull. I'm running the Timney trigger in my Scar17 and it's awesome. Moreover, the 16 is 3.0lbs and the 17 is 3.5lbs (mine is spot on @ 3.5). Like you, I wanted a single stage for this bad boy...the majority of my AR's have Geissele's with a couple Timney's and Trigger Techs thrown in for variation - after all, variety is the spice of life