Hi Burr, does the one you have join up if you scale it down by 1/10 or 1/2 using the steps from here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=3593.3

Possibly that model was built to a tolerance of 0.01 units, maybe making the fillets just sagging away by slightly more than MoI's max join tolerance. A sag of 0.01 units is not particularly visually bad, it can be tough to see it unless you examine things more closely.

The reason why scaling down can make things join up is that when you scale an object down, the gaps between pieces also get smaller as well, so it can put them within the tolerance distance if they were just outside of it before.

In the future I would like to make a way to override MoI's tolerance, but probably something like an override that lasts just for the current command or modeling session rather than something that gets stored in the file and set once the file is loaded - that particular method of having a changed tolerance get set on someone when they don't expect it is the thing that tends to cause trouble.

- Michael