personally i'd always favour - if i didn't have to pay for it at the point of use - using 'paid' / professional mapping for navigation software *where it matters* over using osm mapping, simply on the grounds that where osm is going to be 99% correct, it would be very annoying to end up taking a wrong turn due to the 1% wrong data that somebody - for any reason - could have added; the risk of pro mapping having errors is much lower than the risk of osm mapping having errors.