As others stated, now please work on download performance from SharePoint Online through browsers. Coming from almost any disparate network (my home, multiple businesses' locations) with ample bandwidth (1Gbps down), something as simple as a 4GB file will randomly timeout or the download will prematurely stop when coming directly from a SharePoint Online URL. (And yes, we've engaged Premier on this with no real resolution)
But if you select and download multiple files or a whole folder so that they have to zip & route through a proxy ([dc]-mediap.svc.us) instead of a SPO endpoint this never, ever happens. Downloads of 20, 30, 50GB, etc "just work". So this is definitely where SPO needs some work!
Support for uploading 250GB single files means nothing if you can't reasonably expect to download/upload them without problems...