OK, so I pulled my SOTE 2-packs out of storage today and opened the SLU Doubles protective case I keep 'em in to compare fit and compatability for the Ultra figures. Here is the low down...
They fit, from top to bottom, however, they are a bit wide from left to right. They will still work well if you want to keep 'em in a protective case.
Reikeen and C-3PO fit the best. The Wampa has a deeper bubble and mine fits, but just barely.
So, is you want a protective case for the new Ultra figures, I suggest the Starting Line Up Doubles Protective case!