I don't have the Grim armour, but I've got enough different meshes to run a reasonable test.  I'm at work now, but I'll set something up when I get home and I'll let you know the results.

So far everything I've done in P7 has been a vast improvement.  I have not had it choke on anything, including scene I had made in P6 and P5 that would never render.  I've got scene that has choked Carrara that I'm thinking of bringing in and seeing if P7 can handle.  Not to mention a monster scene (as in huge, not as in monsters) that I created a long time ago in P5.  When that scene, which took me forever to set up, wouldn't render I walked away from Poser for about 8 months.

Anyway, I'll do a really good test and let you know.

I will add, that despite the huge improvements in memory handling (finally writes to disk and such), I have come across scenes that take forever to render.  But, they are ones where I am using every last piece of quality, rendering at 3200X2400, HDRI, 4 raytrace bounces, 6 pixel samples, etc.  The scenes render, they just take time.  (Which is still faster then P6 which cannot get past the rendering shadow maps step!)

Oh, and one more thing.  the longest render times I've had in P7 so far were before I started using the "Render in separate process" option.  That right there gave me a marked speed improvement.

Yeah, i have to say that it is an overall vast improvement that is long overdue.