Two days ago my order for trading HBD for BUSD filled on the Ionomy trading site. This is with a tiny spread of 1.8%. I had put the order up two weeks ago. It was a small amount. I have recently put BUSD back on the market to buy back HBD.
The spread to go from one coin to another often is near 3%. I think stablecoins should be different. Changing from one to another when they are pegged to the same asset, should be very cheap.
There is a 0.25% trading fee on Ionomy. If you want to sell 1.00 HBD to me for 0.99 BUSD, you will end up pay exactly 0.99 but I will get only 0.9975 (as I will pay the fee in this case). On the other hand if you want to buy 1.00 HBD for 1.008, you will end up paying 1.0105 as you in this case would bear the trade cost.
Velocity is really slow. It took two weeks for $10 of liquidity to convert HBD into BUSD. It did happen, though.