Half-Baked Escrow Compression Bitcoin Scheme

So i was thinking about sending all the files to a client as one encrypted compressed file as well kind of like an "insurance" but its not really if you can't unlock anything with out the password anyways. Wouldn't it be cool to unlock files or perhaps even better "blocks" of data according to how much of the amount has been paid for instance if I have a to send file 1.txt 2.txt 3.txt and 4.txt to the client I could encrypt them all and If half the bitcoins are sent only 1 and 2 are unlocked and if all are sent 1,2,3,4 are unlocked. The reasoning is that perhaps the client can review the files to the extend that they wish and when they’ve "seen enough" they can stop payment and continue with more conversing of improvements until futher payment is made... Probably not too practical for everyone to directly sow into the Blockchain or Saotshi client but still a fun idea non the less for a new type of escrow.