Although I've only used SpiderOak for one day, I already have a good feel for it. At least enough for the following observations. I like SpiderOak as whole, but it does have it's ups and downs in comparison to Dropbox:
1. SPEED: SpiderOak seems slower than Dropbox. I have not timed any events, but it seems that way. It might just be me, but the differences aren't glaring anyway. Dropbox does have an option to control upload/download speeds, but I have not found a similar setting in SpiderOak.
2. ONLINE ACCESS: Both Dropbox and SpiderOak allow users to access their accounts online. However, when online SpiderOak only allows for downloads. Dropbox online allows both uploads and downloads.
3. USER FRIENDLINESS: Dropbox is very simple. I believe near any user can easily master Dropbox as there isn't much to tweak. SpiderOak's software is logically laid out, but has many more tweaks and settings than Dropbox. Technically savvy people won't have problems with SpiderOak's software, but casual users might be a little intimidated.
4. SYNC: Both allow for computers to be synced. Dropbox's sync is super easy, as it's pretty much automatic across computers on the same account. SpiderOak forces users to manually setup the sync and it can be a little confusing. On the plus side, SpiderOak allows users to specify exactly what files and folders gets synced between computers. Dropbox is all or nothing.
5a. BACKUPS: Both services backup files to online storage. However, SpiderOak can be set to additionally backup to a local solution such as an external hard drive. This option will greatly speedup restorations, as SpiderOak will restore from the local hard drive first. Dropbox does not offer a similar service.
5b. BACKUPS: Dropbox creates a new folder on the user's computer. Whatever the user places in the folder is automatically backed up and synced. Users cannot backup anything that is not in Dropbox's folder. SpiderOak does not create any new folders. Instead, users select which folders get backed up by selecting them from their current location. The same goes for whatever files get synced between computers.
6. SECURITY: Dropbox centrally maintains the encryption keys. SpiderOak's encryption keys are maintained on the user(s) computer. SpiderOak cannot access your encryption key, which means they cannot access your data in any manner. Dropbox has the potential for employee snooping of user's files.
7. DEVICES: Dropbox can be installed on PCs and MACs, and on mobile devices. SpiderOak can only be installed on PCs and MACs. Both allow for installation on multiple devices on the same account without additional cost.
8. FREE STORAGE: Both offer 2GB of free storage. Dropbox provides various ways of increasing free storage, such as through referrals. SpiderOak does not.
9: PAID STORAGE: Dropbox begins at $9.99 monthly for 50GB. SpiderOak begins at $10 monthly for 100GB.
I have decided to keep both services. I currently have 4GB of free space on Dropbox and 2GB on SpiderOak. I am using SpiderOak only on my main system to backup my scanned files, which are currently taking up around 1.6GB of space. I am also using the option to additionally backup my scanned files to an external hard drive.
Dropbox is holding about 2.4 GB worth of data, but it compressed the files down to about 685MB. That leaves well over 3GB of free space available. Dropbox is also on all of my systems with its way-too-easy-to-use sync. Most important is that I can download and upload files to my online Dropbox account when I'm at work. That feature is indispensable to me.
