Well it seems you are truly informed on the subject, and have certainly clarified the situation to me at least! I was stupid of me to say that "all that was needed was a downdraft", honestly, I know better than that!
You mentioned a downwash speed of 45 KTS in a UH60, I suppose this varies with power power right?
I've been in situations doing ENG in an B206L4 at 8,000 FT AMSL, was hovering with about 80% TQ (no wind), I decided to descend vertically (slowly), so the camera could have a better view of an accident under a bridge which was about a mile away, about 5 seconds later with about 500 FPM the thing was "clearly" in VRS, it shook like crazy, it started wobling slightly, and applying power didn't help at all, on the contrary. At least I think it was VRS.
The helicopter aerodynamics book I have right here states that the actual critical rate of descent to achive VRS is dependant on GW, HD, and "other pertinent factors" but in any case you should consider anything of more than 300 FT/MIN, and nearly 0 airspeed a probable VRS area, I used to think this was excessive even for say 8,500 FT 25 degrees celsius we commonly operate here, now I really don't think this is excessive except when I have lots air below me.
I will definately like to have more info on this subject since I obviously have much to learn, I only have about 2,500 hrs in helicopters, but I have only flown little below say 7,500 FT, this has probably led me to be extra careful with collective application, and helicopter operation, up here the things just tend to drop to ground much faster!
Thanks for your input.