According to Toykeeper, RampingIOS v3 does add a stepped mode option for the D4s. I'm not quite sure from the UI diagram how to switch between the modes, but it's described in her review:
http://budgetlightforum.com/node/61509
I wasn't sure if I'd like the ramping on the D4, and while I think I do still in most situations prefer discrete modes, the ramping is so well executed that I don't consider it a negative.
Keeping your spending down is a very good reason not to buy a D4S.
The next time your collection needs another member, however, if you don't already have one of the Emisar's, it sounds like this latest model takes an already excellent UI and gives it even more options, so it's well worth giving a spin.