That's exactly what i want to do, i'll use the new testflight system integrated by apple recently. That's why i need just a email to start from people who want to join the test.
Everything is ready to start sending invitation by mail.
For people who are paranoid about the security with their founds on bittrex, just create a new account on bittrex and send 0.002 BTC to this account in order to make some trades. My apple store account exist since 4 years now and it's my main job. I won't do anything malicious to steal some BTC and risk a ban from apple. In other words, i won't shoot a bullet in my feets with a malicious app. You can trust me !
For absolute paranoid, you can sniff the communication my app send and receive with something like wireshark. I have nothing to hide and i wil be happy if someone make this test and post the result here to show everyone it's a clean app.