To further clarify...

I'd like to hear what it means to you. There are a lot of threads around here about:
  • brakes to keep the muzzle down
  • longer-than-carbine gas tubes to reduce operating pressure
  • buffer/receiver extension combos to reduce felt recoil
  • triggers that allow one to operate them more quickly
  • etc.

So I'm curious all of these would at least equal, if not be greater than, the sum of their parts if combined and if so which specific parts would be chosen.

as an example,

Noveske N4 14.5" midl-length N4. Heavier weight than a "pencil barrel" to keep the muzzle down, 14.5" mid-length is widely reported to have the least amount of pressure.
Battlecomp 1.5. Battlecomp is clearly the new hotness in muzzle devices, and many here will attest to it's ability to reduce muzzle climb.
Vltor A5 stock system. Another part that, if you read through the threads, is reported to reduce muzzle climb, or at least felt recoil.
Geiselle SD 3G trigger. Appears to be pretty widely regarded as a "fast" trigger, and IIRC it was designed to be such.
Eotech XPS. The Eotech fans all seem to use "I'm faster with it" as one reason they like it.
12.0 (at least) Brazillian handguard. Brand immaterial, but one of the reasons we hear for longer tubes is "driving the gun", so while not a speed issue on an individual target, should come into play on multiples.
Noveske FFL lower. The flared magwell seems to get billed as an aid in speed reloads.
Magpul BAD lever. While having largely fallen out of favor, at one time at least it was billed as being faster on emergency reloads.

My goal here is that I'd like to assemble a gun, maybe two to have a control, with the go-fast parts and the legacy parts and attempt to quantify the gains, as well as be able to switch parts back and forth to really verify. The barrel issue may stymie me, as I'd need to either have it pinned (that won't allow me to move it around) or register an SBR just for this project (and I don't want to wait 6 months).

The other, control, gun might have a 16" lightweight barrel with carbine-length gas, A2 flash hider, Aimpint H-1/T-1, fixed irons (they "get in the way), carbine stock, GI trigger, legacy lower, short(er) handguard (possibly railed) etc.