Well, I have the example of a Slippery Kerblaster used with a Legendary Ranger Com in my assault rifle thread (it’s near the end of the post). I basically compare the damage with 0/5 in Ranger and 5/5 (which is boosted to 10/5 with the Legendary Ranger Com) in Ranger, and even with Ranger at 10/5, the damage increase was only around 270,000 (270K), which isn’t that much.
I’ve tried 5/5 in Ranger with other guns as well, and the damage boost was pretty small. That’s why I personally don’t recommend it. There are better skills to invest in.
Speaking of skills, I would say that of the two, Overload would probably be more useful if you plan on using assault rifles frequently. Mag Lock is pretty good, too, but I personally dislike it because a bad throw can lodge it in weird positions and cause it to miss the target. Also, if the turret is placed on a wall or ceiling, it seems like it takes a few more seconds for it to acquire and fire on a target.