I have thought about this as well, because when KG first came out, it's not like everyone had the mindset of "oh, I will wait for the next three or four years and see all the KG that trickle out so that I may wisely make a decision." Also, with the initial enticing limited offer of stacking depending on how many DK's you had, most of us went for the only options available at the time.
A switch option would be nice, but like everyone else mentioned, a steep price would be good. Much like how the name change system is at least 5000 dp overall, this should be something along those lines.
Perhaps cost 2000 dp as a base, and another 1000 for each stack that you wish to exchange. And on top of that, after you've done it once, it can go up in price. So for instance:
Say I had 3 stacks in Uchiha and I wanted to switch it to Hyuuga, it would cost me 2000 as a base, plus another 2000 for the 2 stacks on top of it. So it'd switch my Master Uchiha status to Master Hyuuga. And then say after that, I want to switch say... a Gai of the Lotus to Warlord of the Kaguya, it would then cost 3000 (because the base would go up since you have already used the KG switch once before) + 1000.
I have no idea if that made sense, and that was just a rough thing I just kind of formulated in my head right now, but I don't know if this helps or not. The reason behind the making the base go up after each time you use the switch function is to discourage people from switching willy nilly.
