Should my PFR% be lower at the lower limits?

[Forbillz]

You should still be raising with JJ even if you expect 6 to every flop. It's about equity here, IMO. You're going to win with JJ more than one out of every 7 times (again, you're assuming 6 to the flop) so it's a +EV move to raise. You may not win this hand wiht your JJ, but in the long run, you're still charging those players with the weakest holdings to call additional bets.