Hey ,
first of all, thanks for your detailed response! 
As for the skylight and lower hemisphere shadowing, I actually havent tried out the differences that much^^ So I will do that to make sure I fully know how its affecting everything. Just did some small testing with it that wasnt so much depending on reflections.
I also have to say that I really love to have everything dynamic. I mean, I can fully work with lightmass and also would say that I quite know a lot about it now, but I really prefer a fully dynamic setup 
Its just less time waiting and more time spent on cool things and finding cool work arounds
About dark distance shadows, yeah I really hope Epic/Lionhead will at some pont introduce a that allows us to lerp the LPV against the ambient cubemap from an unbound post volume. Right now, you can not adjust the resolution of the LPV, so the bigger you make it, the worse the gi and the leaking gets. I found a good value is at 6000 units and an injection bias at around 3. However, that also means that the volume is quite small and shadows will get black pretty fast. Lerping those two would really help keeping shadow color nice outside the LPV.
Regarding your bug report…we (me and our graphics/all-around-genius programmer :D) already commented on it 
About deactivating the shadow casting…take the skel mesh that you use for your BP setup und do :
://imagizer.imageshack.us/v2/xq90/842/1cuw.jpg
Tested it on 4.1 and got no crash
The console variable is: r.AllowStaticLighting=0
Yeah man…didnt mean to offend you (I dont think you are but just sayin^^) Its quite hard…PBR is still something people are struggeling with. I mean…I see a lot that are just so used to fake things that they just really cant let go and adapt
And you can totally see it in the material work. Anyway, I love it!^^ And by the way, I also really dig your material definition!
Yeah man, same goes for my preoject with the Bugatti. Lets see how long it will take me to finish it off besides all the other stuff I am working on xD
Hey, thanks as well and looking forward to see more!
Cheers!