The 1 TB storage that you get with regular Office 365 memberships is the regular OneDrive service, not OneDrive for Business. It works pretty well with large accounts.
Also, it's likely that your past experience is with the old OneDrive for Business client. Last year the normal OneDrive client learned to sync OneDrive for Business data, and reliability and performance improved quite a bit.
(I worked on OneDrive until last summer, but I don't currently work at Microsoft.)