At first glance, I thought that the Implacable Destruction stance was kind of on the weak side (and maybe mathematical analysis, which is admittedly not my strong suit, will prove that it is), but upon further reflection, we may be selling it short since it applies to every missed melee or close weapon attack, without regard to weapon type, feat selection, power selection, etc., etc. If I've learned anything from playing and reading about 4e, it is that the more damage you can squeeze out of the system, the generally better off you'll be. With this in mind, at least 7-10 points of guaranteed damage per attack seems like a nice boost.