|Keep It Simple, Stupid
Yes, of course you are correct. It's probably even a smidgen faster to just assign a 1 to $| than it is to perform the computation involved in incrementing. I don't think I've ever run into a situation where I wanted autoflush on a filehandle sometimes and then go back to buffering, but I'll keep that in mind.
I do like the use of setting the autoflush locally in your other post.