PADJ and POPSPIN -
Great discussion here. Makes me appreciate the variety and differences between these references even more. Makes the 5021 and 5032 seem different enough to appreciate them both even more - not just an evolution of the Portuguese a Perpetual.
I am practically a "neighbor" too. Living in Northern Vermont, I get down to Manhattan monthly. Let's consider a meet up at the Flagship boutique to inspect some more Perpetuals!
I completely forgot about the complete/incomplete numerals on the 5032/5021 dials. The dial diameter and case diameters are the same. It appears the numerals are a little smaller on the the 5032. Not sure about the subdials. I sort of like the incomplete numerals on the 5021 - more about their larger size.
With regard to the movement. IWC is always investing in their movement technology. The cal 5000 family is one of the very first production shifts toward all in-house in a line of series production. Introduced in the Portuguese 2000 in the year 2000. The latest calibres, with the Glucydur beryllium alloy balance are not as pretty to look at as the former screwed-balance with their heavier, larger, eccentric swing pattern - but, I bet it affords better adjustment/regulation, and service times. It doesn't 'cheapen' the movement - but wears/performs better over longer terms.

Here are a few frames of animated photos of the back of my 5021, taken a few years ago. You can see the magnitude of the balance. Also note the bridge engraved "sixty six (66) jewels". In fact, the 50611 has only 64 jewels, but the original design had 66. IWC already made some bridges with "66" and they put them on the watches...