I think the effect would work better (in the current implementation I mean, as you say your idea is awesome... but I can't see it ever happening) is with fewer, but more powerful, champions. Keeping them rarer and scarier might give you pause for thought. Three in a pack? You may as well just go caster>everything else as normal.
Or maybe you can only get more than one champion where one of the champions is an orange name. So champion minibosses can get champion minions but the rest of the time just one champ at a time. Just to keep them 'special'. Otherwise you may as well have just buffed all the mobs' HP, DCs, To Hit/Dam, spell pen and SR a little bit on each difficulty and walked away without going of the trouble of doing a new system at all.
However, tweaks not withstanding, I'd rather have the champion system working well than not have it at all. As a casual player, I think this as a concept this is starting from a position of "full of win, needs refinement" for me.