Mac,
While it is true that the trunions are no harder than the receiver material, your statement is a bit misleading.
The fact is, that, regarding the stainless Red Label guns,
the receiver is incredibly hard and as such the trunnions are also incredibly hard!

How hard is incredibly hard you may well ask.
Well they are so hard that to fit bushings for the strikers the only way to machine the action face is to use EDM or Electric Discharge Machining as normal tooling is not in the race!

They are so hard that they are capable of shattering a hardened center punch!

If you want to know how hard they really are take a stainless RL action to an experienced engraver and ask him to to cover it with rose and scroll!
Hope you can fight!

Sure you could have the receiver anealed for machining or engraving and then get it rehardened but that process brings problems of its own.

The RL receivers are hardened RIGHT THROUGH the steel.
Many other actions have case hardening which is no more than a surface hardening of a few thousands of an inch depth on the outside of steel which much softer underneath!

As far as the hinge pin being integral to the action frame being a drawback, you are correct as far as tightening a loose action goes, as the job is not as straight forward as with an action that has a renewable hinge pin.
But the job can still be done.

One of the most highly praised and respected SxS double rifle actions is the long bar Webley and guess what?
Its hinge pin is an integral part of the action too!