If you are having regrets upgrading your Single-Collateral Dai to the new fancy, but not quite widely used (MCD) Dai. You can simply exchange it back using a little known feature in the MakerDAO smart contract.
Smart contracts can be compared to the mechanism of a vending machine, which are programmed in such a way that after a user selects and pays for an item, it will be dispensed accordingly. In our case, the smart contract allows to take back the DAI and swap it back for SAI.
We've tested it and it works pretty flawlessly.
First you need your DAI sitting in an Web3 Ethereum wallet, like MetaMask on Chrome/FireFox/Brave... Then do the following
Tada! The good old SAI is now in your wallet again, and you can use it anyway you want. Like paying off your CPD or just putting it back on to Compound to generate some sweet interest rates, because the DSR rates are pretty bad.
