Looking for some opinions on 300xs vs 250xs outboards. Any key differences between the two (other than 50hp)? I don't see many 300xs listed with more than 300ish hrs, do they tend to need a rebuild or new powerhead at that point? Do the 250s have a longer lease on life? I know it all comes down to how they are treated/cared for, but does anyone have enough experience to speak to the "all things being equal" scenario? While throwing out opinions feel free to weigh in on 300x and 300R as well.

I’ll try. 300xs/ great fuel economy for 2stroke, some issues with air compressors.
300x/ one Mercury’s best 2 strokes ever, HP rating is actually higher. 30% more fuel usage than xs.
300x/ Four stroke probably your best choice if you can find one. $$$$$.

Premium fuel only in the 300XS's and produced by Mercury Racing, and will typically have a Sportmaster lower. The 250 ProXS (later models) are fishing motors and usually have a standard or torquemaster lower and run on 87.

There were a couple early years (04-06) 250's that were 250XS models, and were also built by Mercury Racing. These are normally called "Gold Block" 250's as opposed to painted black later model blocks. They are also said to produce a little more than 250 hp (270-280 ish)

Both engines will run 1000 hours plus before rebuild. They do not turn high rpm. 300x same thing. The 2.5L engines would be worn out with 300 hours. I used to rebuild my 2.5's at 100 hours.

If you are concerned have a leak down test done. Two strokes need rebuilding with more than 10% I have about 300 hours on my three 300X engines and leak down is 4%. Almost like new.