New community user mods almost ready for show time - hold on to your socks.

Thanks for your reply.

CDU unit?  I was simply going by the Carenado Proline 21 User manual that came with the CJ2.  Personally I've always used the term 'FMC' as well. 

After a couple of hours using the CJ2/GTN I think i've managed to answer my own questions. I think I confused the logic by switching too quickly between ILS VLOC approach to GPS using the CDI  button and disengaging NAV at various times, purely to try and understand the modes better. As you do.

I found the Garmin user guide useful in a basic sort of a way but managed to dig out a couple of excellent videos that weren't around when I purchased the 750 early on.

So no worries, case closed. I like the CJ2 a lot and would recommend it.  

Regards