Get the single stack. No doubt about it. Mags are plentiful and cheap. Mags for the DS one are NOT. I don't even know if commercial non-norinco mags can be made to fit.
If you want a quality double stack 1911, look at a ParaOrdnance.
Especially for your first gun, the single stack Norinco is the best value going. As mentioned, you might want to contact Gunnar at Armco, as he sells 'cleaned up' versions with better componants and a trigger job. VERY worth while!
Also, if it's your first handgun, consider a Norinco NP29 (if you can find one). It's a 9mm 1911, and has extended safety, slide lock and a beavertail saftey. VERY good value for the price.
The 1911 in .45 and the NP29 were my first two handguns. I've since upgraded, but it is an awesome place to start!