Any Security Concerns with iCloud Syncing vs Dropbox Syncing?

Dropbox also syncs to the cloud, so in effect their is no difference. Your 1Password keychain is always protected by your Master Password.

These are some links you may find useful, thought some get very technical. Its a personal decision each user has to make.

http://learn.agilebits.com/1Password4/Security/1P4-security-changes.html
http://learn.agilebits.com/1Password4/Security/security-overview.html
http://learn.agilebits.com/1Password4/Security/keychain-design.html

This article is from 1Password 3 but I think it still does a good job conveying some of the details.

http://help.agilebits.com/1Password3/cloud_storage_security.html

There are also a series of discussions in the lounge section of the forums which you may find useful. http://discussions.agilebits.com/categories/general-lounge

Now personally 6 years ago I went through the same concerns you are now. I was hesitant to use Dropbox or then MobileMe's iDisk the precursor to todays iCloud.

After spending time here and being a user of 1Password 2 then helping to beta test 1Password 3, I found though my own experiences that I wholly trust the team here at AgileBits. If they recommend it then it's good enough for me. One of the reasons I liked the team from the beginning is they say we like it but here, look at the details and make the decision for yourself. Over the years they have included things like wifi syncing for those whom simply do not want to use things like iCloud and Dropbox.

I later went on to become a moderator at the Dropbox forums as well, partly based upon my interaction with it because of the folks at 1Password.