Is the barrel guaranteed 1MOA or better, and do you need to hold to that shooting beyond 300m? That's the question to be answered. Otherwise, most free floats are a waste of money.
As for venting, it does reduce weight. It's meant to allow air to cool the barrel, and that's because the weapon is intended to shoot a lot of ammo in a short time. I.E., machine gun fire. If your budget is to blow away 500 rounds at a session, sure, get vented. If it's 50-100 rounds over two hours, no need.
The typical medium game hunting rifle has no need for free floating, as most will shoot 1-2MOA without it, the barrel and ammo being the source of accuracy, and optics allowing you to aim so small you can discover the limits. After that, a free float just keeps the barrel from being pushed around and making it inaccurate, just as a good trigger helps to reduce the shooter drifting off target before the round can get out of the barrel. At 2MOA, a rifle will still hit a 10" circle at 500m, and that's still 1/2 the size of a lethal hit zone on a 150 pound live target. It's why the Marines still issue the M16A4 with standard rifle handguards. The quad rail for mounting numerous old school issue lights and optics is used a lot, but that's the primary purpose. You need to be a skilled shooter to see the difference. I bet you notice a bipod does more. It's certainly cheaper. And a lot of hunters are now selecting shooting sticks - just long bipods for field hunting.
For all that, the lever .30-30 has taken more deer than any other rifle; with the tube magazine banded to the barrel, and a handguard attached to it, it's certainly not free floated.
If the AR has a problem these days, it's with all the technology being thrown at it without an understanding of the basic principles of accuracy in firearms. It's a specific hierarchy of results in this order: Optics, bipod, barrel, ammo, then free float, and trigger dead last. Far too many start backwards.
Why optics first? Well, the Army spent $$$ on red dots and scopes, rather than more range time, and that's because you get more accuracy return for the dollar on that than an equivalent amount of ammo down range. Look at the DMR rifles, two major improvers of accuracy, optics and bipod. Those aren't $500 Krieger subMOA barrels, and ammo is just issue, not even handloades specifically optimized to the gun. The free float, because things need to be clamped on it, it's issue, and importantly, the DMR doesn't look like a specialty sniper dude. That's been spoken of by the Army as a significant reason why they don't want the M14, it looks too different to Haji, and they know it. Last, the trigger. The new issue sniper rifles in .300 Win Mag won't have adjustable triggers. Expert Professional decision there. They will be sniper grade, but accuracy doesn't take a major hit for the lack of a screw. It's easier to adjust 10,000 coming off an maker's assembly line annually. The few thousand triggers the Army buys can be finessed by the armorer as needed, not tinkered with by users not MOS qualified. Kinda arbitrary, but that's the Army.
As long as the conversation on venting, etc, is for a high rate of fire, obviously not precision rifle thats a one man user, ok. Perspective gets tweaked out of proportion all too often with guns, and there's a lot of getting the cart before the horse on the internet. Keep the big picture in mind.
, get the solid ones. Structurally, they are stronger and look great.