Zerkarn

You got it right for the most part. They act the same as the Beam and the Blast, but use different recharge times and deal more damage. Basically, you get a second, more potent Blast and Beam on top of the other three powers. I can't confirm if Disruption Blast has a bigger area of effect though. I personally am going with mace mastery just so I don't have to fumble to and from the mace.

Besides, you can always respec or make another build. Hope this helps.