Thank you to all for sharing your thoughts.
There was a sale price on Fluid Mask that elapsed yesterday, and I let it pass because I spent some more time with it on some clear sky backgrounds that I found in my archive. I watched a bunch of tutorials and gave Fluid Mask a good trial. I ended up thinking that the clear sky examples I worked with were just as easily masked with Photoshop's built in tools.
I do want to learn more about Fluid Masks seemingly unique Color Workspace selection interface. It seems like it is a great idea but I get the impression that Photoshop has remarkably similar functionality hidden within an overtly different workflow.
I find the brush cursor (the over sized cross hair) and the brush edge hardness in Fluid Mask seems crude compared to what you can work with in Photoshop, but I find I need to use the brush cursor, as both a brush and as an eraser, to clean up in Fluid Mask as much as I rely on brush work in Photoshop, so the less effective brush control seems like a significant downside.
The Edge Blending function in Fluid Mask seems nice, but when I use "Refine Edges" in Photoshop I have already prepared the edges with varying and appropriate degrees of hardness/softness with my brush selection choices so the global refinement of the edges is very much a refinement. With Fluid Mask, the Edge Blending is an absolute necessity. With the less nuanced preparation of the edges, which I seem to be constrained to with Fluid Mask's limited brush control, the result of Edge Blending seems crude where it needs to be subtle and insufficient where it needs to be pronounced.
I am going to spend some free time continuing with tutorials and the thirty day demo, but I think I am used to making much more precise masks using hand painted techniques. I am hoping to find a circumstance where Fluid Mask really impresses me as a special case time saver. The Fluid Mask approach seems thoughtful and ambitious, yet I suspect that the content I usually work with is just too complicated, as an agnostic field of data, for time saving systems to achieve the results I am looking for.
I guess I'll dive in to Topaz Remask when the Fluid Mask demo runs out.
Thank you.