I haven't had those issues regder, and I've crossed the country on backroads several times using my Nuvi loaded with routes created on Tyre, Tyre to Travel, and MyRoute. It does require that you add enough shaping points to a route that you plan on something like MyRoute in order to get it to translate properly to the Garmin, because the two different mapping programs obviously use different ways of calculating a route. I encountered that issue just last night while mapping a route to the Back of the Dragon; I had to add an extra shaping point because the Nuvi wanted to route me onto I-81 briefly when I uploaded a route created on MyRoute, where the MyRoute file routed me on surface streets. Adding an extra shaping point solved the issue. Continued experience with the program and using MyRoute routes on the Nuvi have given me a pretty good feel of where and how many shaping points I'll need to make it seamlessly translate. If I'm riding through an urban area and I want to specifically follow certain streets, I just make sure I add enough points at turns and intersections so the Nuvi will keep me on that route. If I recall correctly from my past experience at creating a turn by turn route for the MABDR that could be used on a Garmin, the maximum capacity for a Garmin .gpx route file is 250 waypoints; that limitation did make it impossible for me to create one continuous route for the MABDR (since I wanted to make sure I didn't accidentally deviate from the MABDR), so I broke the MABDR down into the individual sections.
I wouldn't try talking anyone out of whatever software they're comfortable with, and we're both in agreement that Basecamp sucks. I just haven't experienced the frequency of errors that you have when using non-Basecamp programs, so my go-to mapping programs are MyRoute and Rever. Like you, I stick with what works best for me. As I said earlier, the Garmin is becoming less and less important to my navigation. it's just simpler for me to program a route on MyRoute and upload it to my phone, where both Rever and OSMand can access the same file (plus I can link the phone to my comm unit so I can hear the turn by turns). Using the Nuvi is getting to be more out of a sense of nostalgia than anything else.