I would say the reliability of the M4 far outstrips that of the 930 SPX ... and I own a 930 SPX. - Mudinyeri
Have you had problems with your 930 ? Everything that I have read from owners, they have said it's rock solid, no malfunctions.
I don't know, I actually am a little partial to the Bennelli. I have heard that th ecollapsable stock on the M4 is not adjustable - it's either completely extended or completley collapsed, but there are corners in my house I wouldn't want to go around with a full stock. I don't think I would mind having a short stock. But I don't know...
The other thing is it seems really difficult (and confusing) to get the collapable stock version of the M4.
I don't think the 930 can be fitted with a buttstock that is going to collapse.
When I compared the two though - I sort of came to the conclusion that they are about the same as far as reliability goes.