First off the original Sea-doo starter was designed for the engine and model it was put into. The majority of Sea-doo related starter issues are from “water damage” or just plain worn out. 80% of 2 stroke watercraft that come through our shop still have the original starter from the factory “15-20+-year-old” starters. We have used aftermarket starters on many 2 stroke and 4 stroke jet-ski’s and they work ok but we have noticed a lot of failures after a year or 2. The main reason for short term life is simple, They are cheap! The starters are built with the cheapest components the manufacturer can find. We have seen starters meltdown, short out, and components literally come unglued internally.
Almost all Watercraft starters sit low in the engine bay. This can be an issue if water is present in the hull and most all watercraft at 1 time or another have moisture and water inside. All starters are sealed with o-rings at the base and stem of the starter but that may not be sufficient or work at all.
The foremost issue with O.E.M starters vs aftermarket is cost. O.E.M starters can be expensive. With Amazon and eBay in competition with other reselling outlets along with ease of order often leads to the cheaper quicker option, and for some this option is fine. If your budget is small or the funds need to be invested elsewhere, an OEM starter is out, but expect what you pay for. The aftermarket starter may last a few years or may never work.