This thread is great and just what I was looking for. My unit was just replaced under warranty and the rebuild of my settings etc. Garmin suggested that I do not reuse my previous saved profiles - so i have had to reset my unit and BC and have forgotten much of the research I have done to learn it all... now I find this thank you and learn more.
Unit is a 650. Loaded with City NV, US Topo 24 and Canada Topo 24 (which is nicely routable)
1 - The Garmin tech told me that once a route is made in BC it will NOT reroute/recalculate when uploaded to the unit. Unless you breach the parameters of the unit - ie. number of viapoints or have a different map. It will not assume the settings on your unit. These settings are "set" in BC and attached to the route and will not change when adding the route to the unit. Or when navigating. The only changes occur if the unit recalculates during a trip and you can set it to not do that. This seems born out by my experience but the rep could have got me wrong...?
2 - Can you clarify as I forget now if this works - but - When following a route and needing to get off the route for gas etc. I have stopped navigating and dropped a waypoint at the turn off. Then I route to gas and if needed navigate back to that waypoint, (or follow my auto track) and then start routing again (on my original BC route) and the unit will pick up the route where I left off. This seems pretty simple and easier than stopping and editing a route.
3 - I created a 182km route using BS 4.1.1 using the route tool and then shaping it to my needs. The track conversion info gave me over 1800 points - and the unit handled that route fine. But I might be confusing the issue.
As your attorney, I advise you to buy a motorcycle. How else can we cover a thing like this righteously?