I voted No because I always considered HARP a fantasy thingie (especially with Cyradon), and I never thought PSI fitting for fantasy.
Only reading the posts HARP-SF occured to me, but I've no interest for that. (We tried it once with RM-rules:
"You're aboard the ship. What do you do?"
"I'm the engineer, right?"
"That's correct"
"I'll go to the... what, machine room?"
"Okidoki"
"Everything up and running?"
"Yes. Ship is in good shape."
"Allright, I'll go back. Did anything happen?"
"No".
It just didn't work for us. I know it can, but it just didn't...)
Anyway, what I always liked about GURPS was how everything could be thrown together. So, if there was a book about PSI (or if it were part of SF), it would be a nice thing to have rules for, very generally.