"since some players frail with the index and some with the middle,logically there should be no reason,why a player cant frail with both is there?or perhaps there is."

In the beginning, you really need to pick one - I strongly recommend the middle - and stick with it.

Once you have mastered the basics the finger issues goes out the window - but for the first six months you really need to focus on getting the basic motion down and the only way to do that is to be consistent.

Picking up and down is going to limit you. Alternative fingerstyle approaches will work for a song or two, but that is it. Every song will have to be arranged and memorized individually.

Get the frailing strum down cold - get it "right" - and everything you know from the concertina and your other musical pursuits will fall right into place on the banjo.

-Patrick