I'm admittedly no 3D modeler by profession, but I do need to make some 3D animations and illustrations for work projects. I'll chime in as someone who's also fairly comfortable with Blender, but there are some things that just feels awkward about using it. Maybe it's the way I model, but I can never seem to squeeze the performance out of it that I need to. I see people model these crazy advanced scenes with advanced lighting, reflections, and shadows, but my relatively simple models seem to take forever to render and don't look as good. I get the sense from reading Blender forums that the developers are somewhat antagonistic about the Mac platform, and that there's not as much interest for optimizing it for the Mac. I can only feel this is going to become a bigger problem as developers start moving away from OpenGL toward stuff like Vulkan, Metal, and the new DirectX. I seriously doubt we'll see Blender move to support Metal.
I admittedly haven't used C3D enough to truly get the hang of it, but the biggest thing I see missing from building these models is physics simulations, specifically smoke. It'd be great if C3D 7 could also have more robust smoke/hair/fluid simulation in addition to rigid and soft body. There's just such a huge gap between Blender, free, and a commercial package that can do everything that Blender does. If I could pay a few hundred bucks for a package that has as much power as Blender but in a cleaner, OS-optimized way, I'd do it in a second. But stuff like Modo and Maya are way more than that. And, out of Silo, Strata, and C3D, I think C3D is probably the most robust.
I just need to try remaking one of the animations I've made in Blender in C3D and see how well it works.
I'm still wishing the upcoming app could be distributed through the Mac App Store though. I know the MAS is largely abandonware by Apple these days, but it sure is nice to have all of my apps and updates come from a single source.