The GS lit II gets a whole bunch of nice damages to bonus (lightning blast, lightning burst and holy) and the occasional lighting proc. Plus the dice is [1.5] 1d10.
With my first arty, I couldn't wait to make one, so I made a +++ first. For its relatively cheap cost, it's very effective. I sometimes prefer it still over the Lit II - and you get a raise clicky, which comes in very handy.
After I made the Lit II, I started making a GS Min II - mainly because of the Lord of Blades quest. If you run out of sp, and you don't have a metalline weapon, the Min II comes in really handy (or when trash is immune to lightning). But it's quite expensive to make as a side weapon.
I just pulled a level 21 Nightmare repeater - the nice thing about 20+ level repeaters is that their damage dice is 2[1d10] and then they have a lot of goodies.