Also Ovi Maps (free) works just fine on the i8910 (with a little bit of work).
When you say a little bit of work, I am having a problem with Ovi Maps in that it will not load the 'Drive To' screen once a search result has been chosen, the voice is there giving directions but the screen will not load. Any suggestions?
This will be of no help to you... but I weigh in with an opinion -
I've never used the i8910 for business purposes, it has always been too buggy, etc. and new ROMs = security issues; but I do use the i8910 handset for leisure purposes. As such, the GPS function has always interested me and I have tried out pretty much every solution going. My conclusion: I've always used a third party GPS, in the end the i8910 solutions are just too much trouble. My current device: a Garmin 3790T, which I would recommend. It, too, has some teething problems, but the fact that 99% of the time it just works for me, saves me time (and therefore... money).
I trialled out for a long time the Route 66 software on the i8910, but as this was removed after every re-flash - and at one point I was re-flashing at least twice a month, I just gave up reinstalling any software back on the i8910 after a reflash, except Opera and Google Maps (which, as we know, still does not have turn by turn given S60v5 rather than Android 2.1+).
Sorry for this bit of a non-post, but...
Good luck! all the same.