Well and per my understanding both perform the same .. Underlined are some Basic Differences
1KZ = 8 valve- SHOC_ wastegated turbo
1KD = 16 valve-DOHC- VGT turbo
underlined are the difference between the turbos ...
Wastegated turbo
A wastegate is a valve that diverts exhaust gases away from the turbine wheel in a turbocharged engine system. Diversion of exhaust gases regulates the turbine speed, which in turn regulates the rotating speed of the compressor. The primary function of the wastegate is to regulate the maximum boost pressure in turbocharger systems, to protect the engine and the turbocharger. One advantage of installing a remote mount wastegate to a free-float (or non-WG) turbo includes allowance for a smaller A/R turbine housing, resulting in less lag time before the turbo begins to spool and create boost.[1] (source WIKIpedia)
VGT Turbo
Variable geometry turbochargers (VGTs) are a family of turbochargers, usually designed to allow the effective aspect ratio (sometimes called A/R Ratio) of the turbo to be altered as conditions change. This is done because optimum aspect ratio at low engine speeds is very different from that at high engine speeds. If the aspect ratio is too large, the turbo will fail to create boost at low speeds; if the aspect ratio is too small, the turbo will choke the engine at high speeds, leading to high exhaust manifold pressures, high pumping losses, and ultimately lower power output. By altering the geometry of the turbine housing as the engine accelerates, the turbo's aspect ratio can be maintained at its optimum. Because of this, VGTs have a minimal amount of lag, have a low boost threshold, and are very efficient at higher engine speeds. (source ; Google )
I own a 2002 1KD powered Prado and i simply love the engine and its performance ... but one has to keep in mind no engine is bullet Proof .. if you maintain it properly it gives you no Problem 
