Are there any disadvantages to converting a road wheelset for sscx? I have a set of C-4 wheels laced with Sapim CX-Rays to Alchemy ELF/ORC hubs. Spoke count is low though at only 20/24 (I weigh 155lbs). I'd like to save some money on my new build by running this wheelset but will I regret it down the line?
Those are sweet SSCX wheels; just make sure to get the chain-line set up perfectly and all will be well. Also, keeping an eye on the bearings and internals throughout the season will ensure that everything stays in top shape.
The Belgium love Elfs and Orcs, Elfs and Orcs love mud - so there you go - a perfect match :)
As far as regrets go - with some TLC those hubs will last forever and rims/spokes/nipples are cheap. Even if you do trash a wheel, just get your local LBS to build a new one around the hub. BUT (big but there) if the thought of some clydesdale putting his meaty foot through one of your sweet wheels during some CX race mayhem is too much to bear, maybe you should just buy a cheap set of Mavic Aksiums off of CraigsList and save yourself the worry. It is cyclocross after all and everything on one's bike has the serious potential of becoming a sacrifice to the angry Gods of CX.
If I were you, I'd not run the rear for SS. Remember you'll be crushing a gear, and I'd want more spokes for the load. As David stated, I'd get a simple 32-hole rear, or wheel set. Not really a lot of reason for higher end wheels in cross, as you'll beat the crap out of them. You can often find used wheels in this configuration for very reasonable prices.
Most of my wheels are pretty simple builds. One might consider a King rear, simply for ease of use (really easy to change a gear) and durability. But not much reason to go too far (unless income comfortably permits).
Best of luck!
I am amazed at how durable modern wheels are, the road wheels would probably be fine for most cross courses.
I am not really into equipment, but I recommend using the road wheels on some courses and getting some cheaper wheels, as David and Peters recommended. That way you have a spare wheel or spare bike. If it's a rough course, use the cheap wheel and the road wheel becomes a spare. Reverse that for "Grass Criteriums", using the cheap wheel as the spare. This also has the advantage of getting the feel of both wheels. I suspect that you won't notice much difference between them, especially after caking on some mud.