yeah, low and mid is usually desired in MX. The biggest problem is making smooth power, so it's all controllable and you don't have problems with traction. You might be better off with the dual 34mm's. They'll definately flow A LOT more than a single 35. You'd probably lose some HP but might make it a little smoother w/the single 35. What kind of port do you have? If you're really using those dual 34's to their potential and you want a 2 into 1, then you could look into getting a 2 into 1 w/a 40 mm Lectron carb. But you don't ever need a 2 into 1 intake for MX.
I'm not too familiar w/ Power pro pipes or 2 into 1's. But I've heard quite a few people say 2 into 1's have a lot of bottom end. To keep some top end, another option would be PTR mids or possibly FMF fattys if you're on a tight budget.
BTW, don't change your sprocket set up if you like how it feels. Going with a lower front sprocket will just get you shifting more. I would run as tall of a gear your motor can easily pull.