I have the Garmin Nuvi2555LMT and I use it for both my truck and Ultra.
For the price it seems to be a pretty decent unit. For the motorcycle - essentially if I just put in where I want to go it takes me there on roads that the UNIT calculates based on it's settings.

For the last 2 days, here and there, I've been using a number of online mapping sites like google, mapquest, basecamp(for garmin) and HD's ride planner to try and load a route to the GPS.

Basecamp sux and I've come to find out it's a beta version. Difficult to find destinations and creating routes are awful.

Google - super easy creating routes, but loading to my Garmin(have to use a plugin) sometimes work, sometimes does not, when it does the route is not usually correct. Also, you can't save a route and then export to the gps, you have to do it in reverse.

Mapquest - essentially the same as google, a little easier to load to the Garmin. I did not spend too much time with this one tho.

HD RidePlanner - Easy to use and loads easily to my Garmin - but you have to put enough way points into the HD map so it 'keeps' the route you want. When you export it to the Garmin - if you don't have enough waypoints, it may recalculate your route to a different route based on it's calulation mode ie. 'faster time', 'shorter distance', 'less fuel' etc. My concern tho is that with all these way points, it'll be a pain in the butt with all the updates on the screen as you ride along the route. I'll have to check that out - I'm creating a small route now that I'll use later to test this out.

So, bottom line - HD Ride planner seems to be the best if you have the correct number of waypoints.

With all that said, if I were to get the normal HD type external GPS - I assume it's a Zumo ?... who on the forum has one where you can plan on the HD ride planner and it takes in the route exactly as shown on the computer and what model do you have.
Thanks
PS. before anyone flames me out on why ride with a GPS, just ride the bike - I do that for about 50% of my riding - the other 50% I lead a group of 25 - 50 bikes on several hour to several day trips in places I'm not familiar with, so the GPS does come in handy.

 

I've found that with any mapping tool/software the addition of waypoints are necessary. I use MS Map Point and select the avoidances features in order to keep off Interstates & highways. I've attached a screenshot of the output which I usually print and upload into the GPS.

 

I have been using Map Source for years and can't figure for the life of me why Garmin discontinued this. Easier on everything in all counts. I have Base Camp, but never use it. In fact, when I got my new computer earlier this year, I called Garmin and kissed a lot of *** to get them to send me the down load for Map Source. You mite try this, some of there employees have a way to do this if they will, don't know.