Not at all really. If you are having fletching contact on the bottom of your hen vanes (first off you should be able to see the plastic streaking on your forks and the black rub on your vanes) then you have your arrow doing a big upwards kick right as it comes clear of the bow. Those ST blades, because of their surface area, won't help you any when it comes to getting your arrow stabilized. If your arrow starts out pretty dang stable (as it should with a tuned bow) then its a moot point.

Because the surface area and leading edges of mechs are closer to that of a field point... that is why they tend to act more like field points. Fixed blade heads magnify tuning, form and contact issues... which is part of the reason why its good to broadhead tune and sadly its also part of the reason some folks get frustrated and just screw in mechs and let it ride.

I shoot STs myself, and don't think I'd fool with much else really personally. Don't get too frustrated, its probably something simple really.