If you go Mugen, Losi, or Xray I dont think you will be disapointed. I have a Losi 8ight T and have to say the conversion mount from Losi is pretty slick. I also agree with Stum that if you are racing you wont need any more then 4s.
I have ran Losi 8b and 8T and had a blast with them. I also will say the SC8-e was fun but has its place.
Now I am moving into the luxury department with Xray rigs and all I can say is "wow" over the quality. I was so impressed with my first xray the XB8 that I bought a XB808 and XT8 with a buch of stuff I am selling off. I also have to say that Mikes work on his mounts are amazing and the quality fits the Xray very nicely. You can see my xb808 build thread in the truggy section if you like it has a really nice 3 piece mount. IMO also if you racing a buggy is much more nimble and easier to get the hang of.
Here is my latest build that I got yesterday.....saving for mikes mount now.
side by side to the 8ight T
Now the 8ight is for sale on RC Tech LOL these are pictures from today.
Good luck in your adventure!!