It would be very interesting to see injury statistics comparing the 500's to the 800's.. The 500's were evil, but if you stayed within bounds, they were semi predictable. The 800's, with all the gadgetry, you never know when it might short circuit and throw you to the moon.Just off the top of my head, , Rossi Pedrosa, Depuniet,, , Melandri, Capirossi,Aoyama, and who knows who else have missed a race or races this year. Going back, Hopper, Lorenzo, add name as you think of them. The 800 has been a very dangerous machine, considering it was devised under the guise of safety.
Don't know about injuries but i have found this list of total crashes per weekend. Over all classes.
Estoril 2010 – 128
Donington Park 2007 – 109
Le Mans 2009 – 96
Donington Park 2005 – 93
Estoril 2002 – 90
Valencia 2008 – 83
Phillip Island 2008 – 83
Donington Park 2008 – 75
Suzuka 2002 - 75
Le Mans 2003 - 72
I think like you said the 500cc's could really bite, but many knew the limits of them. Guys like McCoy who where over the limit most of the time did feel it. The 800's have a very high limit, but it's hard to pinpoint that limit. But once you go over that limit you'r really screwed.
That's the way i see it.