Don't declaw, here are some alternatives...
You might be pondering getting a sphynx and having it declawed - we warn against this because it can cause permanent issues in the brain of your beloved baldy, and will cause him to act out in unusual manners. We recommend training your sphynx not to claw up the furniture - do so by buying a little water pistol and shoot that sucker when he's a bad kitty - he'll get the idea of who's in charge real soon. Don't go and buy a super-master-blaster that will knock your 5-year old across the yard, fully equipped with dual pressure pumps and a backpack resivior tank - just get one of those small spitting squirt guns.
If your sphynx insist on scratching something up, pick up some scratching posts or something similar that he can call his own. Alternatives to clipping the nails are having your vet actually apply a small bead of plastic to the tips of the claws - dulling them out temporarily.