I'm just looking into that. I've got two older, identical, Sony Xperia T phones, both have the same Android version.
One has v5.8.2 installed on it and the other one has v8.5.2 installed on it.

So far I noticed the navigon.db file is NOT exchangeable between the two versions which means, either way you go, you will
need to enter your favorites, manually.

Both have a different look and feel to it. Further testing will be needed to see if the newer version works smoother on the
same hardware.

TDR