Well, seems I've caused a bit of a stir here. And, looking back on it, I guess I really didn't explain myself; what I did is there, but not really the why I came to do it this way.

As both PaQ and Michael have mentioned, the best way to get a SDS mesh from a NURBS object is with human judgment via retopology. There's really no magic way to get the "right" mesh when you deal with trimmed NURBS surfaces. Now, if you only have fully non-trimmed surfaces, then you actually CAN get an SDS surface from it without much fuss at all; the CVs of a NURBS surface act the same way as the control points on an SDS cage (they both follow b-spline smoothing), provided all the surfaces that you want to connect together are at least G1 in their continuity. This is actually what Maya's NURBS to Subdivision conversion aims at; it will untrim everything before conversion too, since it just doesn't want to deal with the mess of trying to figure out what to do with the topology around them.

Before now, I would do things the way PaQ describes them (import the high resolution object and retopologize on top of it), only I'd do it in a poly modeler instead of something like Topgun (mainly because I haven't looked at such tools yet). There's actually a rather good tutorial for using the tools in Modo for this very purpose here. However, this really just felt tiring. Now, from watching videos of Topgun and 3D Coat, they do retopology in a way that's faster, but I'd still have to do the whole thing.

So, one day I'm looking at the mesh output of MoI when I turn the angle way up. And by golly, it looked rather nice! Not perfect by any means, but it put the edges in the right place to hold a curve and didn't muck up the model with a ton of triangles. So I went down the path that led to my current method of trimming the mesh to control the points where I want edge loops and exporting problem parts separately if that helped. For most of my hard surface modeling needs, this actually did a damn large chunk of my retopology for me; I just needed to clean up the flow from some surfaces into others, and maybe normally retopo some more annoying parts. I also, if it looks like I need to, import a high res version and use Modo's Constrain to Background feature to rework the lower poly onto the higher one (for times where the SDS shrinks it too much or I need to retopologize a decently curved section from scratch).

The whole point of this method is, really, to just save me some time. I know it's a rather sick and twisted thought process of taking the sexy-smooth NURBS surfaces and faceting them up only to smooth them again, but if I could just plug these NURBS models straight into a game, I would! It's just an odd method of work that I've found works well for me. Now, if all I wanted to do was a high poly render, I'd just forgo all this mess, export a high poly from MoI to ZBrush on and then just take that back into Modo (or Maya or whatever) for rendering. For animation destined for render-only, I'd still kick out a low-poly version for proxy, but I'd not care much about it being SDS ready; keep the animation proxy light and looking something like the final object and just swapping in the high-res version for render.