I have tested this for my own Mastodon instance too.
Although I didn’t get to the point of actually configuring it (just made some tests of DCS acting as a public S3 bucket), I found the load times through the share service quite slow for end users compared to other solutions.
That makes sense due to the decentralized nature of the service, and can be solved putting a nice CDN with cache in front of it, but you need to take care of that.
Edit: quite slow == 200ms of load time without cache for a picture of ~100Kb. Not too bad but on an scenario of a timeline loading lots of media, it can be noticed.