[neilball]

Well from what I have seen KNX uses a single twisted pair cable to provide power and data to their modules rather than Cat5e. You may be able to use Cat5e but it will not be to standard which might have operational issues and therefore may not be accepted by KNX installers.

If you have star wired a single Cat5e cable to each lightswitch then you may also rule out some systems that require keypads to be wired in series i.e. loop from one keypad to the next. If you pulled in 2 cables then you don't have this issue but you do need to keep an eye on overall cable lengths.

So you need to look at the wiring requirements first before you can draw up your manufacturer shortlist or concentrate on Rako which will not need the cables at the lightswitch in any case.