AR quad rail system....free float or drop in??

[TDQ64]

What preference do most have when installing a quad rail forearm on an AR?
Free float ? Or save the $$$ and go with a drop in replacement?

Also it seems that most Carbine drop ins are 7", my factory forearm on my Armalite is 8".....Just move the front site rail back?

What about simple add on rails to the factory forearm as opposed to replacing the whole forearm?

Is it really worth the extra $$$ for a free float and why?

Thanks for any help with this...........

[Kaos]

free float aids in accuracy and generally the barrel can cool down faster. I wont run an AR without FF I have decided.