I would only consider a FOSS cryptocurrency app where I could and HAD reviewed the code for phone home of my wallet details as otherwise I would suspect the app of being able to 'rob' me at any time by on command, time delayed, or randomly execute a transfer of my cryptocurrency to a wallet accessible to the devs. Remember that there are no take-backs or appeals with a transfer, it is P2P.
I also want to state for those who have been fed misinformation, the way blockchain works it is even less annon than transferring money bybank transfer, paypal, or or credit card; essentially it is like cash where every transaction and holder is indelibly recorded on the banknote/bill, announced over the radio, and recorded in a public almanac.
I would not be surprised to find that blockchain based pseudocurrencies were designed by an American three letter police or intelligence agency to have a way to track the flow of black money even when transfers were done offline.