Pork Butts - Multiple Smalls or 1 large?

I'm pretty new to smoking...this will be my second butt.  I'm planning on smoking some pulled pork for a crowd of 30 and was wondering if it's better to get 2 larger (11-13 lb butts) or several smaller ones.  The ones they sell at my local big box market are more like shoulder steaks in the 4-4.5 lb range.  I would imagine it would take a good deal less time to cook several smaller butts than two big ones.  Are there any disadvantages to this?  Any help is appreciated.  Thanks.