Just a thought about trying new maps in an old Quest.....
I have had my Quest1 for years and my experience regarding map upgrades (I've done 3) has been that as each map release gets more detailed, the unit can't seem to cope with the amount of processing required to make calculations (well, that's how it appears to me at least).
I stopped at CN9 because even with that, the recalc times are so slow if I get off route, by the time it recalc's I am too far away from the last point where it started the recalc, so it starts again and I am stuck in a 'loop of recalculations' so to speak.
These days I plan all my journey's on the PC and download the routes, then use the Quest with recalc turned off.
I don't think there's anything wrong with the unit because with the older maps it still works fine (unless someone here has the latest maps and they are working ok in their Q1. Please let me know if you have succesfully used them).
I just wish they had upgraded the processor, I like the Quest. I'm not bothered about fancy postcode finders, MP3 players and Bluetooth etc (what's wrong with typing an address anyway). I have been all over the place and the Quest has never let me down and never failed to get me to where I wanted to go.
Then again.... maybe a Z660 might be tempting