I haven't tried the kf5 squared though it's been said to be more airy than the original v5. Granted I haven't used an authentic but the v5 in my opinion isn't mtl. Wide open it's ok as a restricted direct lung. The lower air settings I find awkward, too tight for restricted direct lung, too loose for proper mtl. Then again everyone vapes different. Phil Busardo for example is a mtl vaper but he seems to enjoy loose mtl vaping. It just makes me cough, like shit or get off the pot. Tight like a cig or loose enough to be restricted direct lung lol. The v4 was a lot better for mtl.
Again just my opinion but I don't believe there's any one size fits all swiss army atomizer that does mtl and direct lung well. If it claims to do both it usually sucks and doesn't do either well. Or more likely a direct lung or restricted direct lung. For a reference, not necessarily the vapor production or flavor, but cigalikes have a nice tight draw similar to smoking. So did the ego vape pens like the halo triton, ce4's etc. They have really narrow chimneys with the tiny high resistance (responsive) coil inside the chimney, no wide chamber. The air inlets were extremely small pin holes, but they're sucking straight air. Compared to a cig where puffing on one the air/smoke was drawn through packed tobacco and then through a restrictive filter. Vaping lacks that, instead it's more like a wide open straw. So air flow has to be super tight to mimic a proper mtl draw for me.
When I watch Phil vape he does this kind of primer puff or two, does a few mouth pulls back to back to back, then inhales. Like he's getting the vapor going and getting a mouthful before inhaling vs a single puff into the mouth, then inhale to the lungs like most people smoke. If you like a looser mtl you might like the original v5, if you're after a tighter mtl pull I'd say look for a v4. If it's restricted direct lung, consider the v5 wide open or the v5 squared (most open of the v4/v5/v5 2).