The KLN90B doesn't do non-precision (VOR,NDB) approach overlays, fly the approach with the GPS but the pilot monitors the needles and DME.
Do you realise what this involves?
GPSS, LPV, EGNOS. The last two are "vapourware" in Europe.
You can fly NP approaches using the OBS mode, perfectly well. In Europe, a lot of the GPS overlays are incomplete anyway.
For GPSS, you will want to install an EHSI, or a "glass" implementation of that e.g. G500, EFD-1000, etc.
The moving map will also be an improvement.
That's true
