So
buy a 510 and try it with a 901 atomizer? Trying to follow as best I can, haha
No, actually I meant that along with a 901 being able to fit your KR8
batteries, you could buy an adapter that will allow the 510 to fit them as well. This would allow you to try all 3 types without buying a bunch of batteries that are only good for one atty.
Most of this is largely irrelevant at this stage, just be aware that there are more options if you decide to try other atomizers after you purchase your initial kit (whichever you decide on).