I used the search but only one post yielded. It was someone wanting advice on which free float modular to get. I have a very simple question. Other than the accuracy gain and aesthetics are there any other reasons to go with a free float rail system?

Depends on what you are going to do with the rifle.

A FF will be slightly more accurate depending on how you hold/rest the rifle.  Soldiers and Marines qual to 300/400m with non-FF barrels so unless you are going for that last bit of accuracy, as you state, mostly aesthetic and a bit more rail estate depending on configuration.

A free float can't make a mediocre barrel shoot well. Every barrel has it's best group, what the free float does is prevent things from making it shoot worse. It keeps sling or rest pressure from moving the barrel around and distorting the sight plane from the actual point of impact. Mount the front sight to the tube and it goes right back being distorted, altho less. Free floats can be more rigid than a barrel but there is no guarantee, and nobody tests to see how much deviance their is.

Because of that flexibility no scope maker warrants their optics if you bridge the mount from upper to front rail. They claim that the tube moving around will bend the scope tube. If you are building a rifle to a high precision, they help.  Using them as just an accessory mount, not so much. The cost is 10x higher compared to screwing something down onto a handguard.

On a hunting carbine, there isn't much to gain, 2MOA will hit a ten inch circle at 500m. Good enough for deer. A woodchuck, prairie dog or antelope gun would benefit but the need is less important than a good barrel in the first place, with tuned ammo and a great scope. Shooter skill  takes precedence to a lot of addons. Shooters were hitting prairie dogs in the old days without free floats and iron sights.

I put one on my hunting carbine and it was lighter, but the aluminum required a glove even in mild weather to keep from sucking heat out of my hand. When still hunting or stalking for hours, it can make a difference compared to a poly resin handguard.

Because of that the AR pistol is getting B5 handguards. It's not a 500m gun and it certainly will be used in cold conditions. No point to spending at least $75 more to have less.

As for the M4 float, that was an institutional decision by committee to provide a universal mount for all the various accessories in the military. The barrels are milspec 2MOA, no accuracy advantage was intended or needed.  Many now recognize that they are an expensive and relatively heavy answer to mounting an accessory that needs about three inches of rail, if not directly in an existing hole on the tube.

Depends on what you are doing with the rifle and your expectations. many times people have unrealistic thoughts for both.. For example..at first I wa SURE I wanted a Free Float hand guard to be as accurate as possible.

then I thought more about it and tried to be realistic. I am not going into heavy combat, im not a sniper/DMR type guy not a lot of use for them in north central PA. Im not hunting(illegal in PA) with it or shooting competitions with it. Im not expecting to take it into heavy combat not a lot of that in North Central PA either...no Zombies Hmmm..so what do I actually want or need this rifle for I thought to myself..

I want a semi auto center fire rifle and have a hole there since selling the AK74. this solves that point

I want it to be reliable...all the parts im using are from reliable companies, and I didnt go bargain basement on the important parts. im good with this also.

I just simply will not no matter my Red Dawn,Zombie plague, end of the world, type scenarios/ fantasy's  be shooting it past 200 yards tops, past 25 FEET in a house, try to be REALISTIC here in what USE you really have/want for it..I did  and realized...I DO NOT need to wring every last bit of accuracy out of it.. Im also not going to drape a ton of Tacticool stuff off it(maybe just a flashlight...possibly a flashlight/laser type combo deal) but thats really it. so when I finish this build off it will wear Magpul MOE hand guards non free float but at 100 yards or less it wont really matter....probably wont even matter at 200 yards and I wont be shooting over that..because I see/have no NEED to.

So in the end I went with being a realist and deciding what im really doing with the gun and went from NEEDING/WANTING freefloat..to realizing I dont need them for what im doing and will probably save myself $150-200 in the process.

More places to mount cool stuff.
Free-floats tend to get the new accessory mounting systems sooner.
Can be longer, so you can mount your cool stuff further forward, or move your grip further forward.
Smaller grip diameter of some models.
More variety and thus more opportunity to make your rifle unique.
Silencers can be shrouded by a free-float grip for some really cool SBR options.
Aluminum vs plastic (not always, but often).
Can be a weight advantage.

Free float handguards get less heat transferred to them from the barrel, and generally allow the barrel to cool faster.

You can shoot more rounds faster without the handguard getting too hot to hold.

Available for cheap (<$50) and won't make accuracy worse. Why not? All my rifles have FF handguards.

If you're talking rail systems specifically, yes.  Weight.  A drop-in two-piece rail of any make will be heavier than a FF quad.  

As mentioned, size is another reason.  There are some really slender FF hand guards out there.

Personally, I like to keep the amount of barrel hanging out of my handguards to a minimum as well.  FF rails and tubes can be right up to (and even beyond) the end of the barrel.  My 12.5" SBR has a 13" rail, only about an inch of the Claymore muzzle brake protruding.



I also joined the cool kids in running 15" slim guards on 16" guns, and I must say, I real ly like them this way!