In the right group and with somewhat decent gear, its quite easy to pump up the Melee crit to in between 70-75%. I always try to use the Rager slipstones (+3 DA) since (in my experience) DA is a lot harder to push to high levels. For no sane reason at all, I hate it when DA is kinda low compared to melee crit
If there's diminishing returns involved in the melee crit levels, I'd go for the DA ones. BUT - If melee crit affects dmg in a lineair way (as I think it does), then dps wise, the melee crit ones are the better choice after all in almost any situation.
And Rippit, that's a damn good suggestion, thanks!

I was getting so tired of switching weapons to apply the stones.