How does your system handle large files? I have a 20 GB encrypted TrueCrypt volume that I put inside my Dropbox folder. It does syncs of up to 4 MB chunks at a time, when I dismount the volume. It did take me a few days to upload the fresh volume on initial sync.

I'll take the 20 GB offer. I could always use the space.

Price: check out all your competitors, maybe offer a subscription based on usage, at the same time offer free users with referrals for example, but also offer one time payments.

Example:

1. 2 GB free
2. +16 GB for 32 referrals (just like Dropbox)
3. 32 GB with one time payment (as opposed to grabbing a ton of spam, just look at all these "expanding" services)
4. Subscription beyond that based on GB used, and bandwidth.

Zero-knowledge encryption also a plus, so I don't have to use TrueCrypt, but make it optional for those who like to.

I am sure you'll get a lot of free accounts, but a lot more will pay one time for an instant 32 GB. The pros can deal with the always paid version.