I dont' think either one is going to be much better than what you have right now. Bigger tank but that doesnt' mean a whole lot. Its all in the CFM as you know. If the cfm ratings on those two units are correct they may get you by and they might keep up ok.
I think one that would be much better suited for you is this one.
I know its more money but its alot more CFM and it is rated at continuous duty cycle. I think Ingersol rand makes the same unit in a smaller tank also. I didnt' see it on the site though.