Jim's spot-on here, really. 1 x 84 hp is just too tight, for one thing. Plus, a Mantis is pretty cheap...not as cheap as the 2 x 140 Ulicase, mind you, but $335 for 2 x 104, powered is a pretty stonkin' deal. And Tiptop even thought ahead for live users, as they've got their own gigbag customized for the Mantis. You also regain the 4 hp used by the uZeus, too.
Using a bigger cab can also help with sufficient space for some large modules, such as Maths. You won't have to be as concerned with what space those 20+ hp-ers are burning.