I haven't heard the Spatials, but I have owned four sets of Magnepans (MG1, MG2, Tympani IV, MG3.6r) and now own a set of GR Research NX-Oticas.
Over the years, I went back and forth between Maggies and dynamic box speakers. Each time I owned the Maggies, I missed the lively dynamic sound provided by good dynamic-driver speakers. When I had box speakers, which included some well regarded products such as Duntech Sovereigns and Revel Studios, I missed the huge deep sound stage, excellent clarity, and tight non-boxy bass that the Maggies produced.
The NX-Oticas are the first speakers I've owned that deliver the best of both worlds. I don't know if the Spatials produce the same kind of sound, but I would definitely recommend giving OB dynamic speakers a try.