SamC

I was thinkingabout buying an M2 but I have a chance to buy an old "new in the box" M1 Super 90 with a Benelli mag extension for a very reasonable price. Price aside, are there an advantages to purchasing an M2 over an M1. Does Benelli sell magazine extensions for the M2? I was also wondering if the Comfortech stock could be retofitted to an M1. Any advice would be greatly appreciated (I am new to this forum)!