Curvature and IES issues

[Speedster]

Hi all;

Posting this here, as I'm not sure if it's a rendering, materials or another issue.

My DAZ 3D figure is bronze with curvature settings.  Lighting is a basic HDR with an IES point spot.  Model is all SolidWorks.

The first image is a screenshot, baked 2 minutes on 32 cores. Looks just like I set it up.  IES is off.

The 2nd image is a render with the IES on.  Note how the bronze has changed.  And those darned, dadburned, shucks, blasted (profanity not allowed!) artifacts we all keep getting with physical lights.  Artifacts go away with full polish.

The 3rd image is a render with the IES off.  Curvature is OK, but could be better, more like the screenshot.  No artifacts.

Any clues as to what's going on?  No crisis here as it's just for fun and learning, but these issues have popped up before.

Thanks!
Bill G
PS: Painting is "Sunday Breakfast" by George Brandrif, circa 1930.  I tried to purchase this painting back in 1969 for $1800, but it was too big a hit on our newlywed budget.  It's now at the Los Angeles Museum of Art and valued at about $1,000,000!  A profanity is warranted now!