When you load a route onto my geko as a track and then select the option to follow it, it appears on the screen as a thick line to follow, just the same as a route. You leave the breadcrumb line with where you've actually been still. It's actually no different to following a route on the screen when you're using it.
I could run it from the compass screen, in which case you can follow the arrow, but I use that less. On that screen it still comes up with "turn ahead" and stuff like that. The only time it is different is if I added some commentary on a route at a particular waypoint. Very rare I do this – for eg if completely off piste looking at a crashed bomber site or something like that.
To be honest, I usually memorise the route on memory map first – kind of happens anyway as I'm plotting it. Then when I'm out riding I glance at the screen occasionally for reference, but it's not as if I'm glued to the screen if that makes sense? I still use maps too.
edit – oh yes, +1 for the service from garmin, I've found them to be superb