To justified the price difference between the AWD and Performance Model even Elon Musk cares since he has publicly eluded that some parts may be binned or spent extra time in the burn process to make them more appropriate for the higher requirement needed for the performance version. It's just that Tesla has not made this clear if this is indeed true. I personally care because I think it shifts the value proposition toward AWD more if it is just the software. If it is the software only enhancement, AWD will definitely be the more reliable vehicle since it can also take the stress of being a performance model as well. And as a performance model the motors may have higher failure rate after the warranty period is over versus the AWD. This possibility matters to me even if this does not matter to you. But, despite all that, currently, I am immensely enjoying my P3D+ more each day for what it is!
Regarding warranty, I'd be more concerned with the half shafts and suspension than the drive unit. The P is not built any more durably, to my knowledge.
If you are woried about reliability, drive your P like an AWD, enable chill mode, or request a downgrade. Any system's lifetime is related to the usage and duty cycle. If you drive it hard, it will not last as long.