As always, Larry is the final expert on this, so I will offer only my experience.
I can't respond directly to Muskie fishing use of hollow core, but remember that Larry is right about the fly line only having 30 # strength, so the strength is limited to the length of the Hollow Core only. Stopping any fish in its tracks requires the entire line to be heavy, not just the leader. You can have a 200 pound leader, but if the line is only 8 pound test, you won't stop much. Consider your leader limited to 30 pound strength, the strength of the fly line core, and any other reason is separate.
Hollow core is larger in diameter them the solid core for the same poundage. I use it to make some leaded leaders like Larry shows on a few TV shows, so I have several poundages in storage. Because it is larger per diameter, and more expensive, I see no real advantage for strength for this example. You can get solid braid in heavy weights much cheaper.
As for cutting grass, smaller is "sharper". I know a lot of people still prefer 80 pound mono for flipping because it does not cut into rotten logs, etc., due it's large diameter; larger diameter, less sharp. I have one rig set up with 80 floro for that reason. But, for slop, not my favorite for sure.
Yes, hollow core cast like a dream as a leader. Cortland came out with a fly leader (Orvis followed, as did others) that was hollow core braided nylon just for fly fishing. I still have some of them and they turn over a pretty line. If I am tossing super long leaders on spring creeks for trout, well I can toss a 20 foot leader with these. They also do a great job for some of my nymphing as well, but, a straight chunk of heavy mono does an equally great job of handling frogs, etc. For Tiger Muskies and Pike I often use a 30 # chunk of mono with a 16 inch chunk of 100 # floro instead of wire. I usually have to change the 100 # out often when I catch a fish but I don't have Larry's monster pike and Muskie to fish for so going heavier is a waist. LOL
I can see using a heavy hollow core leader with a floro shock tippet, but, it would float all the time and that is not my game. Not for Muskie or my Pike for sure.
As I said before, I do use the 65 # power pro braid in a long leader in the slop at times, when I am having fun only, but I have to go after the fish until I get the leader in hand. I think Larry would say that this is extremely inefficient.
But, I never said inefficient could not be fun.