But look at the difference in reaction between Geordi and Stamets and that's a good example of the difference between the crew of the Discovery and TNG, and indeed the shows themselves. Yeah I know Geordi was a hologram, and it was his own death and not loved ones, but would we expect the real Geordi to question orders at all?

I think everything we've seen of Geordi shows us he would follow that order. In fact, it's almost a bit unrealistic that the simulation didn't show Geordi trying to do the dangerous repair on his own

It's actually a pretty stupid test. One could presume that HoloGeordi didn't volunteer to make the repair because The Test was designed to make Troi realize the stakes of the situation and order HoloGeordi to "his death."

But how does this really "test" Troi's capacity to make that command decision IRL. She knows that The Test is a holodeck simulation. Ordering HoloGeordi to die means nothing to her.

Plus what kind of test is it where she keeps doing it over and over until she figures out the solution. Wouldn't a truer test of her command capabilities be to see if she reacts correctly --by instinct or training-- to the situation the first and only time she confronts it?

In the episode where Wesley took the entrance exam to Starfleet Academy, and he was put in a life&death situation, Wesley thought it was real.