I don't think anybody knows exactly what makes a cue hit well, but the joint material is probably low on the list. Random blind tests have proven players can't tell the difference between joint material based on the hit. My estimation is that any hard joint material, properly mated, aligned and tightened, will adequately transmit the vibration from the shaft to the wood for the purpose of feel. Much of the hit is sound anyway, and most of that comes from the tip end of the cue.
Ivory is naturally a poor joint material. It's hard but rigid and brittle compared to thermoset plastics like Juma and Micarta. The best ivory joints are made by cue maker's who work around this inherent weakness. My Josswest has an ivory joint that is really a thin veneer of ivory laminated to a black linen rod. Because the linen rod is stable and strong, the ivory joint and butt survive taps and jolts. JW has been careful not to wrap ivory around a tight wood core, which will expand and pop it.
Ivory is now a problem material. While desirable in high end collectible cues for valuation purposes, it limits what you can do as far as selling and shipping the cues.
I would say micarta and juma are great joint materials if you prefer the look of ivory. They are durable and impact resistant. Just look for a material that will last for many years without yellowing. Unless you're on order for a Szamboti, in my opinion, forget ivory.
