FYI, not sure if this has been discussed, but the hound variable that affects this is called "Aim Stability". Aim Stability affects how disoriented you get when you take damage.
This is totally different from normal "Stability", which affects kickback when you fire your own weapon(s).
One of the three System Device types affects Aim Stability, but to be honest I usually sacrifice it because I haven't noticed much of a difference. I haven't done any formal testing though -- would be curious to hear others observations been about the value of Aim Stability.
Also, on the topic of the new micropayment downloadables -- I think the light cannon is "special" because it supports 6 ammo types (and of course the only one that matters is the level 3 CE rounds). Not sure I've seen any other cannons that have more than two types (KE and CE).
Personally, I'm running 4 of the new cannons w/ max-CE rounds on a medium mech with a bunch of strategically-positioned shields, and enjoying it. Props to the Brigade for the fun last night, even though I was only around for one match.
-Kordos