Looks great on paper, though I still wonder why no one has released a convincing demonstration of dynamic IRs advantages over normal, static IRs.
FWIW, TwoNotes claim that their virtual cabinets are dynamic. Maybe it's true, but each time I try to use the Wall of Sound plugin, it eventually gets replaced by other options.
Also worth noting that AT5 cabinets are now beyond excellent, second to none.
Overloud's SuperCabinet has got Z-Curve which is kinda sorta emulates speaker dynamics. AFAIC, it works with user IRs as well.
Considering all available options, SpeakerMix seems overpriced. And with its CPU performance, need for further investments as well as not apparent benefits of so called "dynamic IRs" I don't see it being a hit in the already crowded cab sim market.