Jeff brought the musical substance and Kerry brought the image and persona IMO.
Kerry was one helluva player and almost always on his game live until the mid 90's, then there was a marked decline IMO, probably just due to slightly reduced dedication.
Some players (myself included) have to practice very often in order to speed-pick for long without cramping. Age and/or carpel-tunnel can vastly affect this too.
Classic Slayer might not be rocket science or technical flash,,,,,,but I'd just love to hear some of the bashers due a valid War Ensemble cleanly at tempo, and then continue right into another ten songs,,,,,and no ballads in the middle for a break. It's not a just a normal set, it's a guitar sprintathon.
His guitars used to be all BC Rich USA, and they of course used 24 5/8" on many of those original models back in the 80s.
Low string tension and EMGs both promote a very soft playing touch, and that alone greatly reduces flop, thereby negating the need to raise the guitar's action.
When you use larger gauges and/or tighter tension there is the natural adaption of touching the string slightly harder in order to have the same attack sound.
I've never found that larger gauges and/or tighter tension allow for lower action, in fact the opposite ends up being true because you must compensate attack. (IMO)
Personally I prefer turbo slinky 9.5-46 for Eb on 25 and 25.5" scales. Never had a 24 5/8".
Slash uses 11-46 at Eb.
I've always assumed that Kerry only used the EMG gain-booster for leads. His riffing tone was usually quite dry and crunchy.
His Marshall heads were kt88 loaded from about the time he became friends with Zakk. Those lend a drier bark than the typical EL34's more saturated gain.