What's the difference between Henry 547 UniPro and 549 Feather Finish?

I’m preparing to smooth out my 3/4 tongue-and-groove plywood subfloors for an LVP installation, using Henry products per the flooring’s installation instructions and local availability.

I had settled on using Henry 542 Liquid Backer Board to fill in / level out my ~8′ x 12′ "birdbath" area (which goes to ~1/2" in the deepest spot), since it does not require a metal lath for installation over woodsubfloors (I’m also planning on screeding this area to a slight incline to make it flat, but not exactly level). I was planning on using Henry 549 Feather Finish / patching compound to seal the cracks first, and then skim coat the entire floor, and smooth the edges of the LBB. Now I’m seeing Henry 547 UniPro (with the 546 additive) recommended as a universal patching compound / skim coat and am realizing I might not have given that enough consideration, as it looks to be able to do everything I need with one product!

I like that the 547 UniPro + 546 latex additive is reported to give more working time and to result in increased strength and flex (I imagine this is beneficial given the slight flex in my floor boards). I also like that (like the 542) it doesn’t require a metal lath over a wooden subfloor. The downside seems to be that using 546+547 would be more expensive than 542 LBB + 549 Feather Finish: $26 for one 25lb bag of 547 (covering ~20 sqft) + $20 for 1 gallon of 546, vs $38 for a 40lb bag of 542 LBB (covering ~40 sqft) that mixes with water. I can’t figure out how much 546 is required for a bag of 547, just that it’s a 1:2.5 ratio by volume, but as best I can tell it’s more than 1 gallon.

Would anyone recommend either the 549 feather finish patch (+LBB) or the 547 universal patch (+546 additive) over the other in this situation? Thank you!!