I have had good luck with D752's on the rear as a cross over tire, though if the surface is hard and dry this tire gets a little slick. The life I have gotten out of these tires have also been pretty good. I tend to run sand tires because of loose hill climbs. There is always a trade off in performance on one surface or the other when you try to get a tire that does everything.
Try Michelin's S-12. They work better in the sand and mud than a 752, with a little taller knobs, and they cross over very well on the hard stuff. Plus, they wear like iron. Shane Watts uses them for everything, with an M-12 up front. I haven't used the M-12, but I've found that a Dunlop 756 front is tough to beat in the mud and sand, and works very well on harder stuff as well.
if you want a good sand tire you should get the bridgestone M70 rear with the M59 front perfect match up, also a good hard pack tire that works all around for soft-hard would be the dunlop D739, i had both and they work really well, i also had D752's they were also good and the K695 with the K490 is ok