How is your riding? Can you use double reins and always use the rein you want without muddying the signals by accidentally using the other rein?
IF and ONLY IF you know double reins well, a pelham is a good choice. You ride 99% off the snaffle rein and then if you need that bit extra it is there and you can use the curb rein. Similar principle as a double bridle except that in the double, the curb is for refinement rather than extra strength.
I ride xc in a slotted kimblewick, using the strong (bottom) slot, because I am not familiar with double reins and I do need that extra power to keep my experienced and excitable horse under control. I will hopefully transition him back to a snaffle for jumping soon, but I think I'll keep the kimblewick for xc... it's scary enough when you're IN control, why risk being out of control?
BUT, sometimes, a softer bit is actually the best way to go! I had a horse that was very strong and hard mouthed, and I put him in a rubber snaffle... BAM no more pulling, no more strong horse. So wish I could do that with my current horse but Monty's mouth just isn't made for a thick bit.
I know a LOT of people who ride xc in a grackle noseband and 3-ring gag which is something I've been considering trying because where I am, jointed curb bits (kimblewick, pelham etc with any number of joints) aren't competition legal, and Monty prefers a jointed mouthpiece... just takes finding a gag with the mouthpiece he responds best to (flat French link).