Sounds like the same list I have taken to a few gun classes. The thing that has changed the most is my belt. I have gone through a lot of different belts before I found what works for me. One thing I would add is a small personal first aid kit, band aids, neosporin type stuff. I like New Skin, works great on small cuts. And a snack, in case there is not a lunch option.
I am glad I have one range I can draw from the holster. Just does not feel the same shooting from the low ready.
Oh, and extra batteries if you use electronic ear protection.
While I am not fortunate enough to have matching gear and guns I steadfastly refuse to show up without a back up for most all the important parts to and including eyes and ears and batteries for the ears and probably a mechanical set + foamies. From innumerable courses and competitions I have whittled my gear down from a truck bed full to a backpack and a “support box”. The tools and parts in the support box will do just about anything to my platforms short of threading a barrel. I have been the guy that saved someone else’s match or class (including my own) because I had either a) spare parts or b) spare guns and gear.
The gear process is an ever ongoing evolution. I am a minimalist in just about every meaning but rarely did I ever go to a course or competition that I didn’t walk away with SOMETHING new on my “I got to have one of those.” list. Later on in the game I usually came home a little lighter after giving some new guy some part or piece of gear that I had extra or was getting a replacement for. Second hand gear becomes GEAR when you need it and don’t have it or you break yours.