I always use the sling shot method for a couple different reasons.
It's easier for me grab the slide than to hit the slide release while keeping a good grip on the pistol.
If you own different types of pistols it works with all of them no matter where the slide release is located.
I read this from Clint smith I believe. If you have a minimum spec chamber( that's already dirty) and your trying to load a maximum spec cartridge the slide will need the extra inertia to go into battery.
Dink
That actually makes a lot of sense.
Except the extra inertia/dirty chamber part.
Dave