I'm also finding the current MFB less customizable.
Facebolt (Doesn't really matter unless Metal)
Clear Wheel (Also doesn't play a prime part in the MFB)
Metal Wheel (Matters alot, and pretty much does most of the work. Just think about NO MW on MFB. O.o)
Track (Again, Matters alot, but could use more variety.)
Bottom (Also matters a lot, and decides if it is an attack, defense, stamina or balance.)
4D Bottom (Nice addition, but definitely limits customization of MFB)
Total: number of game-affecting parts: 2-3.
and comparison to Plastics.
Bit Chip (Could battle with or without it, but is just there for looks, although i'm not sure if it is heavy enough to do anything game-breaking.)
Attack Ring (Pretty important, cuz' it gives the beyblade different potential.)
Weight Disk (Important as well, and without it, no proper battles.)
Spin Gear (Not to important, unless uses bearings and other powerful SGs)
Blade base (Again, decides if it is attack, defense, survivor or balance.)
Total Number of affecting parts: 3-4.