My zumo 660 doesn't recognize the curvy roads pref, so there's no point in using it and anyway, I find that fastest time all by itself is much more reliable.
So my advice would be to select Fastest Time and un-check EVERYTHING else in the preference pane. Let BC create a route, which will include too much slab, as you note. Then use enough shaping points to force the route you want. Yes, it's a pain, but I've found that you need to do so much pre-flight on routes anyway, you might as well custom build them from the get-go and thereby have full control. Curvy will miss lots of good stuff (I venture down to the NC/TN mountains every year from my home on Cape Cod and have created dozens of routes that are definitely "curvy").
I just tried your addresses and BC's initial take is what you posted -- lots of slab. But to be fair, the choices for good riding are way out of your way and so an unlikely "guess" on the part of any software. If it were me, I'd head up into the Hudson Valley, east across Route 2 in MA, then into NH and back roads to Brunswick. To force BC to do that will require dragging its suggested route and adding some "forcing" points to make sure it survives a recalc in your GPS.
-dan
I'm wondering if the Windows version of Basecamp had the same issues I'm experiencing?
My zumo 660 doesn't recognize the curvy roads pref, so there's no point in using it and anyway
That doesn't matter because your zumo will import the route exactly like it was made in BaseCamp.
That said, the "Curvy Road" preference in BaseCamp isn't quite matured yet (or maybe I should say that it doesn't work at all)