Can you tell me some words I cannot understand clearly.
> a precission of 1.5%
Does this means that input overdrive voltage is 1.5% of the full-scal voltage?
If so, the answer is "depends". I mean, depands on how many overdrive voltage. If it's very small (i.e. several mV) you may need some correction technique. If not, just amplify it.
> I want to avoid the auto-zero-technique (question of design time)
Sorry, I dont understand (question of design time)??
> When using bipolar input devices - what about the non equal base currents when one input is comming from resistive dividers?
Effects, I guess. It will changes the input voltage. you may need consider this and check by simulation.
I hope this helps you.