Free floats are nice because they preserve the inherent accuracy of the barrel, removing the connection of the handguard and sling. If iron sighted, you don't move the barrel around changing the point of impact.
They don't add to the accuracy, a free float can not make a 2MOA barrel shoot 1/2MOA. That is entirely up to the quality of rifling, ammo, and optic, all of which can improve accuracy quite a bit. Then you'd have to ask, "Do I really need to?" 2MOA guns will hit a 10" circle at 500m, about half the lethal hit zone on deer or the enemy.
Of course, that's very sporting on prairie dogs, nearly guaranteeing a miss. Goes to "What range and target are you going to use the gun for?" That is much more important than "What rail do I need?" because the answer may very well eliminate bothering with a rail at all.
Guns are specified by picking the best cartridge and ballistics, putting that in the optimum barrel length, having the best optics and mount, then stock, grip, handguard, and trigger - literally in that order. Getting things mixed around means some shooters put $300 rails on $600 guns and the results are nearly identical accuracy and a $650 gun.
Work down the list and don't jump ahead, but if you decide to, it's your choice. Just suggesting be informed and make the decision you want.
