5 hours ago, Stearmandriver said:

I'm not saying you can't learn from desktop sims, and for practicing flows and normal procedures they're good.  But, especially if someone is new to the plane and learning it in an initial qual course (or refreshing knowledge they've forgotten and are re-learning), there is a genuine threat of negative training.  A person needs to know the plane well enough to know if what they're seeing is correct

Yes, this is quite right.

When I did the 787 rating I spent a lot of time with the qualitywings 787 in P3D in VR. I was able to sit and gain a very good familiarity with the flight deck and where every button and switch was. I was able to learn panel flows and emergency memory items, and when I actually started the course in the full motion sim I was able to come home at the weekend and practice go arounds and manoeuvres, it was a big help.

When we first sat in the sim I felt very much at home and my colleagues watched in amazement as I was able to flip screens around and perform other party tricks , while they spent 60 seconds trying to find the seatbelt signs, they were convinced I’d flown the aircraft before. My scan using the HUD had also been developed by flying circuits in the QW 787 in VR.

iF and it’s a very slim IF at the moment, I decide to renew my 747 rating then I flew that thing long enough, over 2 decades, to remember how it works and where the PMDG sim systems differ, although it is very accurate.

There are licensed desktop sims available for type training. I had one available to me called something like the Boeing cockpit tool. It was so bland and boring that even as I flight simulator enthusiast I never bothered using it.

6 hours ago, Stearmandriver said:

A person needs to know the plane well enough to know if what they're seeing is correct.

Well that will be most definately the case for type rate renewal.