>>- How quickly do you need to save files to the cloud, or retrieve them? Typical business LANs these days are gigabit i.e. 1,000 Mbit/sec. Typical asymmetric business broadband might be 20 Mbit/sec download, 5 Mbit/sec (or less) upload. In that example file transfer speed from cloud to business would be less than 2% of LAN, and upload speed from business to cloud less than 1%.
>>
>>- You may need or want to do the initial data transfer to the cloud via USB hard drive or tape. Uploading 150GB to the cloud over typical broadband upload speeds can take weeks or months
>
>Having USB3 or ESDI disc access makes sense. But the upload estimate seems to be too bad IMO: upload transfer should be ~500kByte/sec. 2 weekends if there is no traffic on weekends, a week if upload is not taxed heavily by normal biz. As docx usually compresses quite a bit, an automated setup where each dir is compressed before transfer and decompressed cloud side should speed the transfer up by a factor of 2 or 3.

I recently set up a small business client with CrashPlan for backup (to a cloud account). We specified about 180GB to be backed up, I think it was about a million files. In order to not interfere with regular business operations we configured it to back up only between 00:00 and 06:00 local time, 7 days a week. The client has 2.5Mbit up, which is actually fast by local small business standards - some of my other clients only have between 0.5 and 1.0Mbit up.

The initial sync started November 16, 2015 and finished somewhere around January 8 - 9 of this year, so just under two months.

CrashPlan does smart, incremental block-level backups with compression, which should be pretty efficient.

So that's one real-world example; YMMV.