And I'll look at
Orcs and the Sun
I would think Orcs like to brag if they are good at something (or better than other orcs at something). Saruman's Isengarders don't appear to mind the Sun indeed, but why? This might be something 'new' that would be beyond Treebeard's general expectations, but the reason need not be because they have mannish blood (the
Uruk-hai boast that they
eat man's-flesh incidentally).
I note that
immediately following the Northerners complaint about running under the Sun they are derided as 'half-trained' mountain maggots, which could possibly mean that Saruman's Uruks are indeed well-trained to endure it easily.
'By the White Hand! What's the use of sending out mountain-maggots on a trip, only half-trained. Run, curse you!' The Uruk-Hai
Of course that may be 'slim' evidence to some, but it looms large enough to me, coming in direct response to this concern from the chief of the Isengarders himself, and considering also that: the troop from Mordor run very well under the Sun too, and do not complain about it... and (by following the description in the text) it appears that even a
few of the larger bolder Northerners run
with the Isengarders.
In
The Battles of the Fords of Isen (Unfinished Tales) Saruman has Dunlendings, Orcish wolfriders, followed by two battalions of Uruks
' ...the fierce Uruks, heavily armed but trained to move at great speed for many miles.' No specific mention of the Sun there of course, but we find they are trained to move at great speed when heavily armed. Also noting:
'It [the word uruk] referred, however, specially to the trained and disciplined Orcs of the regiments of Mordor.' JRRT Quendi And Eldar, War of the Jewels
Emphasis on training; and perhaps Saruman's lot are better trained (in general) than even many of Sauron's Uruks, but Sauron has numbers that Saruman cannot match, so his forces need to be at their best. I'll give you man-flesh (he promises) but you will train to be 'better' even under the Sun.
In
The Battle Of The Pelennor Fields the Orcs of Mordor appear to fight on after the Sun shines (a great wind blew, and the rain went North). The hosts of Mordor, which I would say included Orcs (Orcs that are said, after Aragorn is revealed, to have hated the Sunlight), were actually heartened by the Black Sails. Éomer's words include singing in the Sun as he prepared to face Mordor, and then Aragorn and Company are revealed and a dread falls upon the enemy. Indeed these Orcs do not like the Sun but appear quite ready to battle on when thinking that the ships contained enemies of the West.
Orcs don't like the Sun. Perhaps even Saruman's Isengarders would prefer darkness if given the choice, but in any case the evidence appears to show that the Isengarders are arguably
better at enduring it than others, and even possibly matched by 'larger, bolder' Northerners. Confusion again might arise at Helm's Deep as the Orcs (the Uruk-hai)
and the half-orcs may not mind the Sun, but Gamling need not be equating half-orcs and Orc-men with the
Uruk-hai.
The Mordorians run 'hour after hour' without complaint, and even when they drop back at one point, the text makes it clear that 'the writer of the tale' cannot know (or tell) the exact reason why (the writer gives two options for the Reader to entertain).