I have a Pentagon Elite II, but not the Applegate Covert. The PEII is nice for the price, but has some drawbacks for any kind of non-adrenaline-charged use. The kraton/zytel/whatever handle has very sharp edges that bite the hand when choking up or grasping the knife firmly. A minute or two with sandpaper or dremel will settle that score. There seems to be a brace missing from the hilt design. This wouldn't be a problem in a combat situation, but he extra flex is noticeable when using it as a working knife. The point of the PEII is -different-, but works surprisingly well for stabbing, prying, or other hard use. It is a pain to sharpen, just because it requires extra steps. The finish and steel of the PEII requires some attention to prevent rust if kept in the pocket. CLP works very well, so it hasn't been a problem for me.
I imagine the shorter PE blade would not be as easy to "flip out" with the arc-lock disengaged. The arc-lock is pretty strong, and has not failed me when the knife has been used in a more "utility" (read: abuse) fashion.
I'd personally be interested in hearing about the Applegate, as I don't have personal experience with it.
-Bill