chain wrap on the Duopar is 36T - he designed his drivetrain around that derailleur, also as described in the ad juvela posted
Duopar chainwrap is 2 teeth more than my Cyclone GT RD, and equivalent of Many MTB and long-cage touring derailleurs made today.
Max chain wrap on modern RD is 39T. (people today using giant rear cogs, 42t and larger on their 1x11 get a little more using a RD bridge piece that essentially lengthens the dropout)
Max rear cog on Duopar is 36t, v 32t on Cyclone GT. (though I can't imagine why anybody would want 36t rear on a triple)
His small ring looks to be about 30T, and I'm running 26T granny on my cyclotouriste.
He'd have no problem covering every gear combination.
If you visit IBoB google group, you'll find people who would still choose those components if they were building the bike today.
Heck, look at me, as far as I'm concerned, there are only 2 RDs - SunTour, and modern SunTour copies, post-'88-Campy and Microshift.
As far as the specific derailleur position, it's on the largest rear cog and looks like it will be at exactly 45-degrees if it were on large-large, also correct chain length.
Of course, there is never any reason to ride large-large, just as there is never any reason to ride small-small.
The half-step jump on the two big front chainrings is probably only 3-4T. The purpose of half-step rings is to split the difference on the rear cog steps.
The shifting algorithm with half-steps becomes always shift first in front, then adjust in rear as needed.
(most people have never learned how to ride and always shift in the rear)
A well-thought-out half-step triple (x 6 or 7) will do anything a new compact double x 11 will do, and often better.
