They're a short, quick handing M14. Due to the shortened barrel, they suffer in the long range accuracy a little, but they still sling the 7.62x51mm and are usable out to 400 or 500 yards. The shortened gas tube and op-rod have (in the past?) caused reliability issues, as they were improperly designed. Instead, they utilize/d a chopped down standard M14 gas system.
I have no experience with the SOCOMs. I report back what I've read and been told by those that own them or have owned them. Their quality seems to be hit or miss. For every report that I hear that it is one of the nicest guns that the person owns, I get 2 reports of them being poorly functioning wastes of money.
Honestly, an extra 2 or 3 inches of muzzle length isn't much. If you're drawn to the rails, Springfield can add the rails to any fiberglass stocked M14 that you send to them. There are other companies that make less complicated rail system and/or chassis that are just as stable a platform for optics, lights, grenade launchers and TOW missiles.
I've warned 3 others against buying the SOCOMS. I've had 3 people tell me that I was right after they have to sell off a poorly functioning rifle for half of what they paid for it.