What I don't understand is why they wouldn't make one of those two just have all of the features of both?
I really don't use either because I found that the setup and usage of them was more trouble than the benefit that I got from them. It doesn't really bother me that all of the tools are always available. Otherwise, I'll just have to switch lenses to get to those tools in the cases where I might need them anyway.
And as for screensets, I tried to use them a few times but found them a bit fiddly to get just right and again, ended up where I would want to add one of the screens from a different screenset to the one I was in and ended up either bouncing back and forth so much or just going back to a see all view that it was more work to use them than not to.
It didn't help that there were several changes in a few of the updates that made each one change in ways that made whatever I DID understand about them too fluid with changes that came out to make them better that really seemed more like features that were released before they were ready - kind of like how the comping has changed a number of times in ways that are confusing and different in a not-necessarily-better, but different way - TO ME.
Could be that I just don't know what I'm talking about. :)