Convergence of Design - How to choose?

[joffacn]

Hi
I am shopping around for a 4WD 1/10 EP buggy. Almost ready to put my money down on a Lazer ZX5 with a KM conversion kit.
What I notice is that ALL the top buggies are Centre mounted motor, split battery pack. The difference is some are belt and some are shaft drive.
SO the question is do I go for an "older" kit like the Lazer (plus the KM kit = about $450 USD) or do I go for a "new" kit like the Tamiya TRF501X = $500 USD?
The Lazer comes with Diff and One way for the front and is more sorted. A couple of weak points but with option parts to fix.

What is weak on the Tamiya?
Should I wait a bit for the Hot Bodies Cuyclone D4?

Are the "new" designs better = faster, more adjustable, easier to work on?
Are parts between makers more interchangeable?

How do you weight the different parts to make a decision?
What to do? The money is getting hot.

Jeff