OK, hope i can make this clear enough to understand. I have a 16" Dissipator A3 upper  from Bushmaster in the mail as well as the BMAS 4 rail predator type handguards with them. I bought the rifle ones so they will go all the way out to the end the way the dissipator handguards do. Link to the handguards here in case you need a picture to clarify, http://www.bushmaster.com/shopping/bmas/predator-forend.asp
they are the kind that slip over the rail on the upper receiver. I plan on putting something like the Eotech on this one but have not made up my mind exactly yet but in preparation for  it I  am going to have folding front and rear sights. Now the rear sight choice is relatively easy (although recommendations are welcome based on experience), my dilemma is the front sight. Since it is the dissipator the gas block is under the hand guards somewhere so no issues there with removing the front sight (factory) and leaving it off, but should i put a folding front sight that clamps to the barrel, one that mounts on the BMAS system, or install a block/rail in front of the handguards and the sight on that?
I know prob some of it is preference but I am kind of wondering which way would look best and if any one has pictures of a similar setup be neat to see them and of course if any one has any reasons why one way would better that info would be much appreciated as well.  
thanks...i am looking forward to adding the 4th AR into my family.... :)

The way I think of it is the barrel controls where the shot goes why put the front site on the float tube?  If the barrel moves/warps from rapid fire heat a sight on the FFT won't move with it one on the barrel will.

I think if in your shoes I'd go with the Yankee Hill Flip site gas block assembly.  This site comes in two styles one with a bayonet lug on the bottom and one with a rail on the bottom.  Take a look at eaglefirearms.net, good prices and great service.

thanks, i had not thought about the barrel influencing it....