6s vs. 4s?

I came across another motor that Castle is carrying it's their NEU/MR 036/060/1300V5

Did you find this on CC websight, or Neu? I saw them yesterday on Neu, and looked at CC and did not see them.
IMO the 60 should do fine for a buggy, but that's based on my bashing the 60-2000 in my E-revo with no problems. But if Neu is going to restock all the sizes, they should have a 70 and 80 series coming. You might even be able to find a Medusa 70 around somewhere.