I'm using Keypass with Dropbox to sync the db files. Without 2 factor. If you don't want to put all your eggs in one basket, I'd suggest using separate databases. One for each client is a good method. You have to remember more passwords so your secretpass+clienthash method.

One thing about using a password manager is that it needs to be easily accessible or you will fail to enter all your assets in it, and it becomes less valuable. That's why I use Keypass & Dropbox which makes my passwords available on my Win7 workstation, my Android phone and my iBook.