I have an M4 and a 1301 Mod2. No experience with the M2, so won't comment.
The M4 I have has an adjustable stock. Big plus for me as I need a shorter LOP. I replaced the factory handguard 2-piece plastic covers with a Mesa Tactical Truckee fore end. Before that the gun was already a tad heavy. With that and flashlights on it, it is definitely heavy. A definite upgrade down the line is to replace the itty bitty charging handle and the bolt release. Loading is ok, accuracy is good. I have a Holosun HS515GM on it. It has been rock solid reliable and while I used to clean it every range trip. I don't bother cleaning it anymore, based on the US military reports on its longevity between cleanings. Pistol trip and safety is fine. I actually don't like how goofy the adjustable stock is to operate. Why does it have to turn and then extend...sheesh..just make it simple... I will never sell my M4.
The 1301 Mod2 was a recent pickup - I was sure that the M4 would be banned in March, so I picked this up just in case. Glad I did. I won't lie - I like the feel of it better, shouldering it on my Mr. Burns frame, and feel that ergonomically and usability wise, it is more of a natural fit for me.. The pro lifter is amazing - easy and smooth to load - no biting of fingers. Even though it is a fixed stock, it fits me perfectly - the 13" LOP is perfect for me. The lighter weight is perfect for me. The textured sandpaper like grippiness I absolutely love. It does cycle fast, but you do feel the recoil more due to the lighter nature of the firearm. The charging handle and the bolt release are SUPERIOR to the stock M4. Accuracy is good but I have only used the onboard sights - I plan to get a red dot for it but still musing what to get. A future upgrade for me would be installing a kick-off recoil system. I would love to install something to hang off a flashlight but I don't want to replace the stock handguard - I love the texture and how I can just grip it easily. A mag tube extension with a barrel clamp with an MLOK slot would do the trick but then I will need to figure out how to mount a tape switch. I will never sell this 1301.
Hope the above helps.