Regarding Nylander's development it's not as simple as SHL vs. AHL. I think he signed with Rögle BK and then was loaned to OHL to be able to play in the AHL.
While SHL/HA can be really good for work rate, defensive positioning since it's a defense first league, especially for a team like Rögle was back then (they're up and coming now) but it might not be the best environment for Nylander who needs to develop his offensive game. Liljegren is a good example - he was loaned back and forth between SHL/HA and never got a real role on a team.
Then you have an extreme variety in facilities, coaches, intensity during practice, "pre-season culture" (northern teams often collaborate with the national ski-team, they basically torture themselves. Southern teams collaborate more with the track and field elite).
As an NHL team I'd want my prospect on a team expected to be on the top half and with professional facilities: Frölunda, Skellefteå, Växjö, Luleå or HV71 (in that order). Other teams could work from case to case as well.
Anyway, the decision to put him in Rochester might not have been the worst.