I use glue on most pocket screw apps, including end grained joints (usually just one of the peices). I do agree with FredP however, that glue doesn't take well to end grain, but I believe the screw counters the weaknesses of the glue and vice-versa. Here's why:
Since the glue doesn't "sink in" to end grain and bite into the pores to "get a grip" so-to-speak, it tends to stay on the surface (of the end-grain peice, anyway). With that said, what makes a joint fail is a combination of either, or both perpendicular and lateral forces working against the glued surface, or "plain" created by the stresses we subject the item to during use. The screw works to counter the "pulling apart force" perpendicular to the glued surface, but does less to counter the side-to-side lateral forces. This is where the glue adds strength to the joint - it works to prevent, or hinder lateral forces, i.e., rubbing the two pieces together like you would your hands when washing them - not the pulling of them apart. Working together, screws AND glue form greater stability for the two peices than either one can provide alone. It's kinda like the two bishops in the board game of chess; both have a greater combined value than the some of each individually. IMO.
happy WWing,
Bob