Is the best GP bar compatible with all Best kites... ?

I don't think so, it's a 5 line system where the rest of the kites are 4 line, that means if you take the 5th off to fly it on the other kites you wont have a safety release line.

Yeh thats right. The Redline performance bar is for the 4 line kites and the GP bar is purely for the 5 line GP.

The bars themselves are the same, just the center depower line on the GP Bar is a single line, is shorter, has a larger Chick loop and the obvious 5th line.

Great bars, best they have made yet by a long way.

Out of curiosity what is it that you want from the GP bar over the redline performance bar?