I'm using iPassSafe over a year, First I started to use it without cloud (dropbox) , just did backup with FTP (wifi and my desktop)
recently (4 months) I started to use it with dropbox to copy data using 3G from my iPhone to my iPad (iPassSafe support upload and download from dropbox) , I can tell that it's working great and its very secure since the uploaded file are encrypted (just to confirm ,I tried to view the content with editor and it's totally unreadable).
The fact way I'm using iPassSafe is because I check reviews in the appstore which exist since 2010 in few country and never found one bad review
refers to security, I did find lots of very positives review about it