I do, and so does everyone I know, but it is not actually obligatory. You can send a completely healthy soldier into the Conversion.

>Then again, he's probably just happy to have something to do that
>didn't involve torturing enemy prisoners of war to get the specs for
>it.

I've always just figured that Vahlen just compartmentalizes like a motherfucker. There's a couple points where you click into the labs and her quote-of-the-day makes Shen seem positively blithe.

Of course, my headcanon also says that she suffers from the worst nightmares in XCOM, largely as a counter-reaction against the 'Doctor Warcrimes' interpretation, so what do I know.

-----

The most wonderful thing about BBs
Is BBs are wonderful things
Their sides are made out of iron
Their guns are made out of pain
They're crashy smashy bashy flashy fun-fun-fun-fun-fun
But the most wonderful thing about BBs
Is there is more than one
The~re is more than one!