Agreed. Given the long history of high school phenoms who've plateaued in college and beyond, I generally think the NCAA champion and record-breaker is a safer bet for pro success than the high school champion and record-breaker.
Yes, Valby's injury issues are concerning, but the flip side of that is she's shown tantalizing potential with everything she's been able to achieve on limited mileage. Moreover, she's already proven herself to be a big meet performer at the top level by qualifying for the U.S. Olympic team. I also like the way she showed no fear while racing against the world's best runners in Paris.
Also noteworthy: Hedengren has already been living and training at altitude, so she won't be able to get the boost that Valby can from doing extensive altitude training for the first time.
All that said, I hope both have long successful pro careers.