I have a 1000/500 connection, the downloads vary for me, on average i would say about 150 -200 Mb/s, i have recently noticed while i was  logged into my router, its showing the download speeds slightly quicker, but i'm guessing that the calculations. I probably download a few games a week, i'm too cheap to buy an external hard drive at the moment, so i delete and re download to save space.

I have both and S and X, and they download about equally speed wise, the S is on Wifi too, as i don't use that one for playing online games,  the only time the downloads are super slow is when a new game releases in back compatibility.

Ive also tried changing DNS and using VPN's etc, don't seem to make much odds, im guessing that's just the max we can get from the MS servers and they load balance against other users, they have made some improvements with "Fast Start" so some games will actually work properly before they have fully downloaded, like actually start properly as supposed to the older way, where it would say it was ready, but basically be the main menu. Its still quicker than the PS4 ever downloads for me.