I went the opposite direction, from 100 to 200 and then their max, 400, which eliminated the monthly data limit. I've found plenty of CDNs (Content Delivery Network) that can deliver to me at full speed.
I got the first 67 GB of the download at my full speed. The last 3 GB took over an hour. Wasn't a problem on my end, though. So, the whole download took about 6.5 hours. If you got all of that overnight with a 50 Mbps internet link...congratulations! You've got an excellent connection!
When Superior Drummer 3 was released, the installer .EXE download from Toontrack was super slow (they were getting slammed). Once I got the installer, however, the CDN Toontrack was using delivered at full speed (took longer to install than download the 230 GB).
When dealing with small company servers, you're quite correct. Arturia, for example.
At $10 extra per tier, it's just not enough savings for me to make downgrading worthwhile.