Pushie Enterprises now bring in the G-form Compression Shirts and Crash Shorts and have a few of each size. (Sorry about the pic sizes).
I would call these a secondary armour for DH purposes only in that they are more designed for impact protection as opposed to sliding which is where the hardshells have their strengths, but kinda suck at impact protection. Where G-form come in handy is in the heat shedding department and also lightness and flexibility. They will wick moisture and increase cooling, much like skin.
The shoulder padding is more for the front, sides and top of the shoulder as opposed to the collar bone or shoulder blade. From your description I reckon these tick some boxes. Sizing is a bit of a challenge. I recommend having it tight so the lycra compresses and keeps the pads in place (eg, I'm normally a medium, but I reckon the small although a little snug is prolly the best size. The shorts I use the Medium.
cycotic has great info and sizing with a few vids as well
http://www.cycotic.com.au/brands/G%2dform.html
Worth a look and pushie are always happy to answer any questions via email pushie(at)live.com.au
As a bit of trivia we have sold these to wrestlers / martial arts guys, footballers, stunt guys (The man with the claws will be wearing the full G-form compliment of shins/knees/shorts/shirt and elbows in the next movie
... the main cast and stunt crew as well actually
) and a few DHérs in QLD.
Cycotic and Blackmans are the only stores thus far with stock, but hoping to break into the larger Sport retailers soon.