For spelunking you probably need a neutral white, 80-90 CRI emitter. XM-L2 comes in the colors you need. Bins are the same for XM-L2 and XM-L:
IO has a few high CRI tints and lists the CRI for each one. The copper MCPCBs are good for extra lumens (less voltage sag due to heat), which is need since the neutral tints are achieved with phosphor coating of the emitter, resulting in less light output. But in a cave where natural color is vital to depth perception, lumens are going to be secondary.