Before I pose my question, I will give some insight as per my scenario:

• I work for a small business (cost is an important factor)
• Our bandwidth is limited and would not support an in-house FTP server

We need to share files (mostly pdf, inDesign, Illustrator documents) to our clients, and as we expand, we are finding that our current locally-hosted FTP solution is too slow and is becoming a detriment to our sales team. What we need is a remotely hosted solution to share files with our clients, specifically with the following features:

• Greater than 100gb of secure storage
• The Ability to distribute unique log in credentials to clients, granting access to a personalized directory or folder, while limiting access to other files on the server.
• A relatively simple web-based UI for clients with limited computer knowledge

We have considered a dedicated remote server, and web-based services (box.net, yousendit.com, onehub.com, filesanywhere.com) but I am unsure as per the direction we should be taking - have I left another solution out?

What would you suggest?

Thanks in advance.