The changes to the distribution of multi-hit attacks and to Called Shot modifiers are a result of a few test combats we ran, so yeah, we've played with it a bit. But not enough.
We settled on 5 step wound charts mostly because we think we'll be able to keep them memorised, if we keep the effect elaboration creep under control (lol), but also because with the injury threshold values we've set, it's actually not that easy to inflict several wound steps on the body location with a single attack. So.. It's not as deadly as it may seem.
In fact, without the wound effects & just using the 5 steps of Wounds as HP, it's probably not too different from low rank OW combat in terms of deadliness. It's easier to damage actors, but it's more difficult to do high damage... As long as you stick with single-hit attacks.
And that would be the major weakness of the system as outlined above: multi-hit attacks are stupidly deadly, because if each hit can do damage in excess of DV, then each hit inflicts at least 1 wound step. So.. Heavy Bolters and the like are brutal.
Our preliminary fix is pooling the damage points done against a location (after soak) and treating them as a single hit to that location, regardless of the actual number of hits. My personal issue with that fix, is that it's very inelegant and feels at odds with the logic of the rest of the system. But it does seem to have the desired effect of making multi-hit attacks dangerous, but not ridiculously so.
I wish I had a copy of our WIP wound charts on hand, because I would love to hear what you guys think - especially if any of you would try it out. But I'll try posting them tomorrow.