Basecamp & OSM

Nothing weird. Routing is determined by the map, so the OSM map is to blame.

I propose to go to the openstreetmapforum with this problem.
http://forum.openstreetmap.org/viewforum.php?id=20
It is a map problem and there are a lot of different maps with different properties available, so you should say, which map you use.
If you are able to speak german, you may also go to the german forum, there are much more experts

See this thread too:
https://forums.garmin.com/showthread.php?43441-Bad-quality-of-routing-in-BaseCamp-4-2-1

I agree, that OSM maps can have more problems with routing, but it looks like Garmin is trying to make it even worst.

@sussamb, did you miss the fact Mapsource routes the exact same file differently than Basecamp? Mapsource routes correctly.
Only Basecamp routes the user off on a wild goose chase , totally in the wrong direction.

Again,there's only one OSM map and is used by both MS and BC.

I imported the same "single direct route" gpx file into each then let each program recalculate on its own.

Well I guess you confused me by mentioning OSM maps at one point then referring to an old City Navigator map in Mapsource. I thought you had a OSM in BC and CN in Mapsource.

Perhaps you could clarify exactly what's happening?

Within Mapsource I have two routable maps. OSM generic routable and CNNA NT v 8 plus several other non-routable maps like TOPO 2008, and several other topo maps from GPS FileDepot.
All of those are used by both MS and BC.

I created a 4 pt "direct routing" gpx file with only that one route in it, and imported that one file into both MS and BC. After import, the route shows up as three straight lines 1-2,2-3,3-4 as it should.
I choose OSM map then select that route and have the program recalculate it.
In MS it recalculates the route and directs me correctly
In BC it recalculates the route and send me totally across the state in the wrong direction, and wanders around lost as describe in OP, before finally getting to pt #2.
Both (Garmin) programs start with exactly the same starting info. (same maps and same file), yet BC gets it totally wrong.
We're not talking about a minor turn here or there, or a slightly different choice of roads. Those differences I would understand.
The conclusion is that MS and BC interpret exactly the same data in different ways........but only SOMETIME.......because if I use a different map, they both MAY send me the same route. However, with my OSM maps, MS is always correct and BC is always wrong.

How closely do the routing and avoidance settings in BC and MS match?

Within Mapsource I have two routable maps. OSM generic routable and CNNA NT v 8 plus several other non-routable maps like TOPO 2008, and several other topo maps from GPS FileDepot.
All of those are used by both MS and BC.

"OSM generic routable" is a default name, so there may be a lot of maps with this name. As example, all OSM maps from Lambertus http://garmin.openstreetmap.nl/ get this name. The CNNA NT is a Garmin Map.
I have an idea what could be the problem: OSM Maps have a file identifier called FID, and this FID should be different for maps installed at the same time.
But as example all maps from Lambertus have the same FID. If now there are two or more maps with the same FID installed at the same time, this may confuse basecamp but not mapsource, as the handling of the files is different in this two programms.
You may make the following test to see, if a single map gives the same problem: Open the Lambertus link above, choose your area in "choose a predefined country". Download the osm generic gmapsupp.zip and unzipp it. You will get a file gmapsupp.img.
Now take an USB Stick, create there a subfolder with the name Garmin and store the gmapsupp.img in this subfolder. There should no other maps be installed. If you open now basecamp, you should see the map and be able to look to your routes.
Now look to your other maps, which you have and look, if they have also a name like gmapsupp.img or another xxx.img. If yes, rename them (without changing the .img) so that you have no identical names and store this files also in the Garmin subfolder of the usb stick. If you see now the problems you have reported, you can figure out by try and error, which maps are in conflict. (If you shift the files between the subfolder of your USB Stick and the root of the usb stick with Ctrl+X and CTRL+V this runs very quickly).

Both Duplicated as best I can . Only avoidances Unpaved Rds, u turns, narrow trails in both.

MS- Car/Motorcycle,faster time, road type slider 75% toward major rds, speeds 70-60-45-35-25

BC-Driving profile,faster time, speeds 70-60-45-35-25

See anything I missed?

[All] Maps have a file identifier called FID [and PID], and this FID should be different for maps installed at the same time.

FYI GmapTool allows you to see what PID/FID a map has and allows you to change it (if necessary).

I've found it useful with OSM maps.