With all the foundational piece in place for bonds, this is one of the next steps DCRDEX Fidelity Bonds

For the UI, what we do depends on if we intend to support both the legacy fee and bonds in the next release. I don't think we should give the choice, only bonds.

So, while we transition in development, I think we should start by showing two options at /register - one that uses the legacy fee and one that uses a bond. But since it's only for developers to use either as needed, I don't think we should make it a single polished form with a selector. In fact, two separate forms shown simultaneously where you just use one of the forms might make the most sense. Otherwise if we make a nice selector on a single form, we're going to have to change that when the legacy fee is dropped. If there are two separate forms shown side-by-side, we just remove one when it's time to drop the fee for the next release.