Re-programming to another API is a relatively straightforward task, especially given that I have all the necessary integration test cases in my software. I want to remove the risk of single-point of failure, not introduce another one - by moving my account to one single institution.
It is going to be hard find anyone else that offers the breadth of wordwide markets that IB offer with a good API. I recently switched from IB to AMP and Rithmic API, but I only trade CME and Eurex. I also day trade, so margin requirements are very low means i dont have to keep a lot of money at these firms, but if you hold overnight and have to deposit more i can see why you would want a FCA registered broker.