Since most (if not all) our systema (MR and VV) work is done on a slow basis
Actually, that varies quite a bit. 'Slow' is a relative term. In VV's school there are guys who like to go fast and hard too. It's a matter of confidence, and also a matter of how comfortable you are with being hit. Because if you do go hard, someone's going to get hit hard, and it may well be you. Many people have a hard (no pun intended) time accepting this, until they acquire some experience. But it's all psychological - nothing hurts that bad at the time really, even in a real fight. The big worry really is that you lose control of yourself from a (major/minor) concussion, and maybe some IQ points (which is important for me). (I stopped worrying about my face when I got married

).
There's this one senior student named Sasha at VV's club. Spends half the year in Serbia (where he runs another systema school). His classes are known for the emphasis on the Borba aspect (ie hitting a lot) because his background is primarily striking. I remember once I showed up to his class, and he had a back problem. He knew I had a BB and some experience in systema as well, so he had me be the second banana - show a couple subs, some grappling strategies, be his dummy for hitting etc. His teaching style (which I like to try and adopt for striking) was to show something slow, and then show it full-bore so we knew it would work. For example, I would kick him slow, he'd show the defense, then I'd kick him full-on, and he'd show it again.
Anyway, at one point he had us spar. He had us make a hollow fist for head shots - that way you could go fast, but the fist would collapse on impact, so you'd get some sting, but no major concussion - hit the head with respect, he called it. I teamed up with a (I later found out) a BB in judo and karate, with some attitude. Without getting too technical, I found my relaxed, I-got-hit-big-deal attitude really helped me. Most of his blows went through me like I was water (including a stomp to the head), and I was in position to impart damage very easily. The absorption skill is very important, and really works! I saw the stomp coming for example, and rather than panic, I consciously decided in that half-second that I was too late to avoid the hit completely, so I would just pull my center out of the path, and use the glancing energy to power a spin into my next move. I didn't even get dizzy, and I had him dead to rights in the mount shortly thereafter. This was about a year ago.
Of course, I would not rely on absorption as a primary defence, but my point is that everyone gets hit, and the ability to consciously relax and flow with it really does go a long way to nullifying damage.
In straight grappling it was even more interesting - the judo/karate bb was not a newaza specialist by any stretch, but still, he knew the basics. Pure systema guys (not that experienced either) were beating him! He was a bit upset. In fact, I've found that systema people are damned hard to sub, even people with 1 year experience. Must be all those 2-on-1 grappling drills we do - which can get pretty aggressive, I might add.
VV really switches up the pace of the classes quite a bit, and people who don't visit regular can get a view of systema that's sort of like the blind man feeling the elephant - they get a limited impression, because they haven't seen the whole thing. Unavoidable, of course, but I have come to fully realize that those tapes have very legitamate information, and if you for example, follow his advise given on H2H (assuming you know enough to really understand what he says), you will in fact be effective at speed.
Just make sure you buy the strikes DVD, it will revolutionize your game (well, mine anyway).