This is very much how I've communicated my bass parts for the FSOF album to our Mixing guy!
I recorded on cubase using a focusrite preamp and sansamp etc, then mixed them down and FTP'd them to him!
Anyway, with regards to your situation Chris, I would be slightly inclined to do five tracks, receive the £500, then carry on with the other five tracks!
That way if he's gonna screw you over, you've only done 5 tracks, slightly pessimistic i know, but keeps you somewhat covered!
Good luck, post some links when it's all up and finished
Si