Yeah, that's what I was thinking, something more like a Dominator's Assault secondary seemed appropriate, just take out the snipe and any power_boost/aim/build_up
edit- and without any boosts just give them dmg modifiers of something like 1.05 to 1.125 for both range and melee. Seems like a fair trade-off
Having a mix of shorter-ranged range attacks and melee attacks forces them to stay close to the battle for a good attack chain, and they still benefit from the utility of having some range.
Personally I hate this idea. I like the sentinel as a ranged attacked who isn't a squishy. Mixing in melee attacks means I wouldn't take them, and I'd have a rather pathetic attack chain. Likely I'd just bail on the AT altogether and make a crab instead.
Right now I'm very fond of the AT as a class that can blast away, and have some ability to survive the aggro generated. I already have to get in close to drop my nuke, but beyond that, I like to have distance for positioning flexibility for cones and such.