I would stick with Elinchrom, for build quality. Most studio heads put out a very similar colour of light at full power, then get warmer as power is reduced. You will get more colour variation from different brands of softbox than heads.
D-Lite Ones then? Excellent lights, amazingly small and light, the heads I actually use most. I also use speedlites sometimes for rim, as they're so small you can hide them right behind the subject's head if needs be.
See how much power you actually need. Your affection for grids on everything might make the Ones marginal at 100Ws, though bear in mind that in a studio situation (with no ambient light to worry about) raising the ISO one stop effectively doubles power.
Hard to say no to an Interfit kit when they cost less than a single d-lite.