the two motors are both like 2200 rpmv.
maybe with 6s you want to go with a lower rpm/v motor ( in the range of 1500 rpmv). btw the missing availability of many different windings is the biggest (and maybe only) drawback of the plettenberg.
but i may be wrong and that NEU and/or the bigmaxx run good on 6s. it seems to me you go in a rather high rpm range. i guess correct gearing would be important.
yeh 4s will be pretty fast, i guess nah, i'm just going for super insane crazy!!
I think i'll go with the pletty, primarily because on the website it says that the motor can handle 6s in a savage. Whereas i'm not to sure if the 1515/1y will be able to handle 6s for long amounts of time without something going wrong.