I've also just sold my ZX5. Indeed they can be great buggies, but I dare to question the great value. By the time you've installed the absolutely necessary hopups to make them reliable and up to standard with the competition, they're not so great value anymore.
Also I you drive a lot on high grip tracks (carpet, astroturf), I found the drivetrain weak and unreliable. I blew 4 bevel gears in two months despite rather tight shimming of the gearmesh !
And I was not the only one with this problem. There's a reason why so many ZX5's are on the second marked right now.
It's sold now and it's going to be replaced by a TRF501, Yokomo BX or X-5. Haven't made up my mind yet but the TRF looks soooooooo good .