To stop things getting out of hand I'm placing a limit of 6 dice on my players. If anyone has more than that additional dice get converted to +3s. Futher 5 sixes and six sixes are so rare that I'm not bothering with them. Which leaves me with four possible degrees of success. Here's how it works in an attack roll (I'm using static defences by the way):
- 0 or 1 six
- A normal succesfull attack
- 2 sixes
- If the target is using a sheild its ignored for purposes of soak
- 3 sixes
- The hit was really lucky, and armour is ignored entierly.
- 4 sixes
- A Critical hit, Target is treated as having a Soak total of 0.
Note that this scheme places natural limits on this in terms of unskilled characters, if you don't have 4 dice to roll, then your character has no chance of getting a Critical hit. While at the top of your game (rolling 6 dice) you will manage this slightly less then 1% of the time.
On the other side of the coin if all your dice are 1's then you have botched. And any time you only roll 1 dice that will happen 16% of the time. So make sure to spread your skill points around a little.
As futher encouragement to use skills I'm toying with the idea of setting seperate dice pool limits on attributes and skills, inorder to counter the Mary Sue effect of the unskilled but high attribute character who is good at everything. It all depands how cinamatic you want your compain. For gritty realism, and lots of fumbles you could rule that unskilled attempts only get 1d, though I think 2d (and a fumble rate of 2.7%) might make for a less frustrating play expirence.