My hope is that they will have taken the Sigma user community's criticisms of SPP seriously. I never went for Quattros.
Sigma is a small family owned company that is growing quickly. I think they're very closely listening to their user community.
Respect for their loyal customers is evident in their willingness to support their own mount, though moving to the L mount for everything new.
SPP has been a stumbling point because they didn't realize the need to continue it's development and improvement. The Quattros had to be a disaster financially. I cant imagine they haven't learned from both of these shortfalls. Time will tell but I'm optimistic that they wouldn't be introducing a new camera without doing their due diligence this time.