Reply to Custom Mapping Kontrol S4

I am about to start working on a custom mapping for my S4 and i know there a few different ways to do it, by over riding factory settings or by having two mappings running side by side. Before i started i wanted to get some input to how i should go about this. Im pretty fluent with mapping and I tried adding a few custom commands just to test it out and it seemed to cause alot of bugs and stability issues with the S4 that iv never encountered mapping other midi controllers. So my question is whats the best way to map my S4 with as little bugs as possible.
Also i want to map a button to my S4 that will half and double the BPM of the track on that deck, does anyone know of a way i can achieve this? or at least a way to adjust the BPM past the point the tempo fader will take it.
Thanks in advance.
CC