We've been using them since they came up about half way through our campaign,  I personolly perfer the crit level charts much more then those fixed or rolling to confirm or most any other system I've used.  As a matter of fact tonight for the first time i rolled a six on the crit chart, rolled max damage, and with a +2 enhanced broad sword that my fighter has grandmastery with, so perhaps Im just feeling particularily good about the system now.......

Confirmation roll is about preventing the unsatisfactory result that less skilled combatants deal critical damage more frequently relative to their own hitting rate. For instance, if natural 20 is a critical strike, and A hits on a roll of 15+, while B hits only on an 18+, then on average every sixth hit of A and every third hit of B is a critical.

TL;DR Confirmation rolls make the chance of making a critical hit scale with level.

This is why I introduced the idea of class-based crit results in AS&SH. It makes fighters best at delivering a crit. It does not completely solve the mathematical quandry, but (I feel) it helps.

Ynas Midgard wrote:

(If the others agree, we'll port our current Vikings & Valkyries crew to AS&SH, perhaps even to Hyperborea (they are planning to seek and destroy a wizard who resides in his tower on a misty island; and transported to another world via strange mists is such a Ravenloft-y tribute I cannot resist my inner evil GM)).

Resistance is futile!