Can't answer yourquestion on the losi products because I don't run them. As for the castle I do have one. Its a great speedo and you can plug the mamba max into your computer and program it that way if you want. The only problem with it is that although it can run both sensored and sensorless motors it tends to cog (hesitate) at the start when using sensored motors. It's fine once your moving though. I believe it has something to do with the way the speedo is designed to run with sensorless motors. I know caslte is woring on new stuff as well.
That said you should go to each manufacturers web site and dig up the info on the speedos and motors. Most have it posted somewhere.