I haven't looked into the details but nicely conceived. Working on similar projects, we were worried about the CPOF by using blockchain.info and I've done some work allowing interface to Electrum servers instead of bc.i. However, it can be problematic when combined with Tor, so I'm not sure I'd recommend it in this case.
For the CPOF issue you can also use eligius_pushtx as a backup. Also, v1.1.7 will probably include a pushtx and fetchtx via some public bitcoind node that I'll run myself and you'll be able to plug in your own node too.