But, different brokers will have different margin requirements. Surely those won't always be 1:1.
If you allow margin trades, then you reintroduce counterparty risk. My main goal here was to find a trading system
which eliminated counterparty risk and the need for legal or reputational enforcement.
I see. That does sound like a better system indeed (especially with the borderless nature of bitcoin).
Anyways, there is still a tax on margin requirements because you can't use bonds to back your trade.
As you point out, however, allowing margin trading does reduce the tax.
I'm a bit confused about how your system handles both bonds and 'contingent blocks [aka options/futures]' and the relation between the two (if any).