How about some oppinions about front sights with an M4 carbine.  If you have a Flattop upper with a RAS, which type of front sight would you want in a SHTF or combat rifle?

The Fixed front sight I can appreciate is the most rugged, is always available.... but it could block the use of some attachements on the top RAS and flattop 1913 rails.

The removable front sight, my least favorable option, is quite rugged, but you may not have it when you need it and if you leave it on the gun you still have the issue with it getting in the way of some attachments.

The third option, the folding or flip-up front sight isn't as rugged and could be knocked down in the field, but it does have the advantage of always being on the gun and it will not block any accessories on the rails....

So, what are the oppinions of the AR15.com community?  If you were spending the money to build up an upper which would you use to allow the best compropmise of flexability and dependability?  

p.s. FWIW I have a Bushmaster 20-inch HBAR flattop with the GG&G flip up front as well as several uppers with the full front sight.  Therefore, I am not looking for advise on how these work, I am interested in knowing which front sight you would want in a close combat flattop with RAS carbine upper.  I will buy this in 14.5-inches and it will be used with my M-16...

Thanks

Fixed is best (KISS pricipal).  What could it possibly block that you would mount on top of the RAS?  Certaintly not optics, and the RAS gives you 3 other rails for mounting a light.

NEVER remove the front sight from a weapon you'd truly bet your life on.  Furthermore, on a true combat weapon, I feel the A1 upper is best, w/ a forward mounted red dot or reflex type sight.  Just my .02 worth.

Definitely fixed.

Why the A1 Spider?

I'd vote for fixed in shtf/combat.  Folding for target/range work.  

What 1shot said sums it up.  A1 sights are set & forget - no knob to bump out of whack due to "combative mishandling."  IMHO, a rear elevation adjustment is a nicety, not a necessity.  Fits the KISS principle.