What are the inputs that must be considered when setting the eternal inflation parameters for a PoW coin? From technical perspective, I mean.
From economical perspective, 100 years of growth at 2% APR is 624% per century. Granted, century is a long time, but also the current system with its wasteful resource acquisition and general footprint on pristine nature, cannot continue 1-2 more centuries with this growth rate.
On the other hand, gold production of about 1.2% (historically higher ~2%) can be regarded as near optimal, because gold has held its value vs. oil in the last decades.
If the economic and population growth abate, 0% is of course optimal as you cannot go lower.
=> The quick thinking would point to 0.5%-2% bracket, and it must be percentage, not a fixed amount.
This is a really important matter. A 1%-point fail can easily destroy the coin. (see silver inflation in 1850-1870 for instance how a precious metal was destroyed)