Maybe a stupid noob question but here goes anyways:

Are transmitter RF modules universal? Meaning if I have a KO transmitter can I put in a Spektrum or AE or whatever-brand module and expect it to work?

I understand that I may lose some of the features but will it work?

Thanks!

Generally, unless a module says it is compatible with a brand and a specific transmitter, it is not. You cannot randomly put an Airtronics module in a Futaba radio and have it work for example. If you are buying a non-OEM brand module, you can expect to find a list of compatible transmitters it will work with like, for example again, this one.