My older 705 never worked reliably with .gpx "routes". It would often hang trying to load the route, or announce "finished" at the start of a loop ride. Grrr.

But the .tcx "courses" always worked. It would beep to announce the turn as I was in the middle of the intersection, not very helpful. I turned off the beeping, since I didn't like the beep when starting or stopping, either.

So, just a plain purple line with some arrow icons at the turns worked "good enough". No warnings, no announcements, just the route on a small map. I've used it for hundreds of rides, and that minimal routing works fine. I would just look down occasionally to see if a turn was coming up. I'd zoom out a few steps to see the next turn a few miles away, then zoom back in to the "300 foot" zoom to see the correct side street that the route turned onto.