I'd expect to be required to be capable of testing whatever type of RCD I'm installing, or is present on a circuit I'm working on.
My current Kewtech MFT doesn't do Type B, but I've not installed one, and haven't needed the capability. If you are going to be doing work where these are used, then I'd suggest to include it.
However, I suppose I'm going to eventually come across one e.g. when doing an EICR, and it would be better to be able to test it, instead of having to put a LIM in the box.