I can't go into details, but let me say that someone who would be in the know at AWS, very much off the record, told us not to use their hosted elastic because of how terrible it is.
Some issues: scaling it is manual (a "managed service" that requires direct management to scale is not a managed service lol), the elastic versions supported are usually woefully out of date, limited customer adoption means that the product doesn't get a lot of engineering attention and is just limping along, etc.
