The ZR200 are a solid fiberglass limb similar in material and overall construction to what alot of other companies like Parker, PSE, Mathews, Bowtech, etc... use on their bows (minus the split limb part).

The XT2000 limbs are multilayer, laminated glass/carbon limbs. Because they use carbon they have a faster "return rate" which means a slightly faster arrow. Their overall construction in terms of the contouring, 3/4 inch width and laminated layering makes them an extremely durable limb.

From a practical perspective for the average bowhunter there isn't much difference between the two of them other than the ZR200 limbs are now roughly 1.5 inches longer per limb this year than the XT2000.

Unless you plan on abusing the bow by shooting ultralight arrows out of it (5 grains per pound, etc...) with a heavier draw weight and average to long draw length day in and day out for a good part of the year then I think either limb will suit your needs. If you do plan on putting the bow through alot then the XT2000 limbs would be a better choice.