VRS
May I be so bold as to offer a few of my thoughts on VRS:
1. Levo - as already covered by Nick and Um... yes they will indicate a descent.
2. The descent rate will be high but the instruments will be readable unless you allow the situation to go uncorrected, it then becomes quite unpredictable.
3. Nick, I think the figure of 300fpm used by many instructors is, as Um... says, a sort of "alarm bell" figure, eg, I insist that during the approach, as the speed reduces through 30 kts, the rate of descent should be less than 300 fpm. Bearing in mind that this is being taught to student pilots who need bench-marks in the early days to keep them out of difficult situations.
As far as demonstrating VRS goes, what a silly idea. Just like arterial bleeding, I don't need to see it to be aware of how dangerous it is. The incipient VRS demonstrations given by instructors are aimed at showing the student how unpredictable the helicopter can be if power is applied when in a high rate of descent with low speed and how to recover from that situation by increasing speed. The demo should not be allowed to develop into anything near VRS but simply to serve as a severe warning that helicopters will bite your ar$e if you are not careful, therefore, when reducing speed through 30 kts...........etc etc.
Intentional VRS should be left to you test pilots if you feel the need.