The Biblepay Foundation (TBF) was thought to avoid tax problems for the individuals to liquidate the charity funds. On the other side, it had the risk of increasing centralization.
What do think is the tax problem? If you sell BTC, you are taxed. But you give to a charity, so that is a tax benefit. I don't see a tax problem... maybe accounting and paperwork problem mostly.
DASH is centralized to some degree. You need some centralization because the wisdom of the crowd is not ideal. We need a steward who will keep the values of Jesus Christ and align BiblePay correctly to those values.
we still need to incorporate some sort of company to allow us to develop the iOS wallet app
This is good reason to have a non-profit. IMO, run BiblePay like a business. There are decentralized aspects which is good use case (like charity proposals), but other aspects need protection and centralized is a good idea.