In general, the rating system will not give you any boost in SEO, what they will do is increase your CTR, especially if you get rich snippets (showing stars in Google results)
Since it has its own classification system and is already shown in SERP, it would not touch it. Now, having third-party reviews is important for users who depend on their products, shows more confidence, the sites use to manipulate reviews, that's why third-party reviews are important.
Ratings are not important only for local businesses, if you are selling a product or a service, people would definitely like to see the comments of other users about the service / product.
What you could do is:
- Keep your rating system
- Have a third party review
(2) It would be beneficial for your site to have third party reviews not only for users, but also for your site, users will search for "brand reviews" that, in general, in the first positions are the main actors such as trustpilot, not You have to invest too much time to maintain them if your product is what users are looking for, you will get positive comments that would be enough.
Here is a realted theme of searchenginejournal and rankpay