I also had a rollbag in the beginning and found it quite practical: compartments for the kites, trays for the winders and stakes etc.
But after my collection got bigger and bigger and other kites (single and dual line) were added, I switched to the "zipper styled bag" and stayed.
It is easier and faster to pack the kites in the bag. For handles, lines, stakes and other small stuff (for repair and so on) I have different small bags.
On the field, I reach into the big kite bag and I pull out 1-2 kites for today and the handles with lines are handy in the small handbag. I do not have to look for anything together, forget nothing and am so m.odular.