I'd like to put together or purchase an M4 configured AR15 and I've looked at a number of different possibilities.  I currently have three ARs, a preban Colt gov't model, a postban Colt MT set up for NRA highpower and a DPMS kit rifle.
I would really like to stick with Colt for the
1/7 twist and the extended feed ramps (and for the purely illogical reason that I like the Colt horsey).
I'm not hung up on having a flash suppresor or bayonett lug, but I would like to utilize a collapsable stock.  Are there any real benefits to a flash suppresor as opposed to just a crown or muzzle break other than cosmetics?  A post ban Colt M4 upper is cheaper than a Preban and I could legally wear it on any of my current receivers, even the preban with a collapsable stock installed.
Preban or Postban, what's the difference in function alone, and is the flash suppresor worth the extra money?

(The complete Colt MT 6700C is nearly the cost of a preban upper!)

Thanks for your input,
Larry K

Another [newbie] to welcome. Welcome! [beer]

If you already have the pre-ban recievers I would buy the pre-ban assembly and use it on one of those. The M4 style rifle just doesn't look right without the collapsible stock on it. The flash suppresor does work, and it also looks cooler. Good luck!