I am not a shoer but I will throw in my two cents...
4H must of changed in the last 20-25 years since I was in it if you need sliders to be competitive! Lol!
Yes, guys will roll the toe, basically what it does is make the foot similar to a ski so it can push through the ground better during a slide. My husband refused to do this on my horse because he was used for other things, if he pulls that shoe off that leaves that toe exposed without the protection of the shoe and he could become sore. But of course that depends on how much he takes off to roll the toe.
I have seen some reiners with a lower angle in the hind feet, it makes the toe look long and if I had to guess the theory would be that it makes more surface to slide on, I am not sure, just speculating. I think it looks ugly and unbalanced.
You probably don't need a full fledged slide plate, which your horse may not be ready for. Where ever I worked horses wore shoes appropriate to their sliding ability. And we did the opposite as most, on the young horses, we didn't shoe the fronts only the hinds. This was to help the horse realize that stopping with his weight on the hind was better than the front.
Since you do multiple events you could do a plain shoe with the heels turned out to help balance your horse in his stops. Some barrel racers do this as well. I am not sure about jumping though if it would help or hinder.
Also turnout is going to be a factor, you don't want a slider with a long trailer when a horse is turned out. They can slip and fall very easily and the trailer can get caught on something and they rip them off. Again you might be able to get away with a shoe with a little left out behind. If he is stalled then it shouldn't be a problem.
I think the best would be to talk to your shoer about all the events you do and come up with a plan best suited to meet your horses needs. Good Luck!
I DON'T LEAD 'EM AND FEED 'EM, I RIDE 'EM AND SLIDE 'EM.