A factory pro unit is usually a 4 or 5 gas system which will tell you much much more compared to the o2 sensor on a DJ250i. Is it necessary to tune one? No, but there can be some advantages. For very high level R&D a 5 gas analyzer might be the way to go.
I’m not sure where your question is heading, but both are very good systems. Normally the operator will have more of an influence in final results than anything. The same bike will report less HP on a Factory pro than a 250i. Typically the 250i will report less than earlier DJ models. The bike is still producing the same power but some guys get caught up in numbers.