I like my SX3 20 gauge a lot. The trigger is not real light but after some gun scrubber and a good cleaning it's much better.
It shoulders well and shoots real soft. It is 10 ounces heavier than the M2.
It carries lighter than it is, don't know how to explain that but it doesn't seem heavy.
I got the Universal Hunter model which has 26" barrel and is drilled and tapped. It's a few ounces lighter than the cantilever model.
The advantage of the SX3 is that those two models will accommodate a red dot or scope. Whether the M2 can be drilled and tapped seems to be open to interpretation.
I do know the SX3 is as simple to disassemble and clean as any gun I own.