Hi mjs - well it depends a lot on the kind of work that you need to do.

There are a few pretty big general areas that Rhino does that MoI doesn't even attempt anything in yet, a few that come to mind immediately are 2D printed output, generating rendered output, and CAM plug-ins.

Because Rhino has a pretty extensive plug-in ecosystem there are a lot of add ons that you can get for it to do many different specific industry things also.

But it sounds like you already have another parametric type CAD program that you use for most of your work already?

As far as surfacing goes, there are a couple of specific tools that MoI does not have yet, an N-sided patch (for filling in irregular holes when doing surfacing), a multi-edge Blend and a surface matching tool are the most prominent ones missing currently in MoI. This is an area that I expect to work on improving in MoI soon in v3 though. But for now if you're doing a lot of advanced surfacing those are probably the particular surfacing tools that you would go into Rhino to use.

But I guess that you are also asking not just about how to use Rhino in combination with MoI but also about Rhino v4 compared to v5 - I don't think that there has been much changed in any of these particular surfacing areas from Rhino v4 to v5.

So if you're using Rhino only occasionally there might not be much of a reason to upgrade to v5 from v4, if you're using it more often for some particular feature then I'm sure that there are all kinds of various improvements here and there throughout so if you use it often then you'd benefit more from an upgrade probably.

- Michael