they are about as tough a truck as you will find.
the HZ is a bit gutless
the 5 speed is a bit better but still S L O W...
the smaller front diff can cause problems but very seldom...
i like them, if you are going to turbo then get the BEB changed out as well
Reading between the lines then . . . .
1HZ - non-turbo - good for @4-500,000 k
1HZ - Turbo - good for 250 - 350,000 k
i must disagree with your assumsions.
Mr Toyota has messed up over the years. if you do a search you will come across a thread of poor design flaws in Toyotas...