I took my XLT to Padre Island in January and it did great. The two adjustments I made to the standard Jewelry/Beach program were to set the AC Sensitivity down to around 57 or 58 and I turned the Pre Amp Gain up to 4. That combination seemed to give me good depth without a lot of false signals.
Also, here is some advice I got from others on this site about beach hunting with the XLT.
Cover the control unit, it isn't waterproof. I used both Saran Wrap and plastic bags from HEB along with electricians tape. Both seemed to work well. The idea is to prevent rain/blowing sand or other moisture from getting into the electronics. Make sure to take it off every evening to dry out and not get condensation in the works.
The coil is waterproof, but I didn't go more than ankle deep in the water.
Be careful about inverting the unit while digging or in the water so water doesn't run back down the rods to the electronics.