@atarian - thanks for the kind comment - I wish my boss would appreciate my analysis as much as it seems you do and the ironic thing about that situation is that the word analyst is in my actual job title
Ahh, crazy, scattered, non-communicating employers, you gotta love them. You're compliment above comes at a key time as I'm getting burnt out in more ways than one.
As far as FPS, to clarify there, I definitely play and keep it locked as well for vsync but for testing I disable it to assess the maximum FPS and impact on table changes as well as even VP software revisions. So, don't take that to mean I recommend at all playing with FPS wide open, it's simply a temporary setting for measurement and....analysis 
I did mention that for sure there is some level of difference with input lag with Aero / DC / DWM vs. it off but needed / wanted it, yes, set on to get stutter free play and no tearing. The thing is that it wasn't visually that noticeable really and that's where I'm surprised some people new to VP can see it but also why I still suspect that standard TVs input lag is easliy half of that situation / problem. As most people know by now, I scrutinize VP in a detailed way and even with that it still took me only until recently to definitively prove that I had a difference in lag between these two settings. And that was only done mostly in how shots worked / were being made a little better for backhands / back angles and balls rolling through the in-lane since the physmod and VPX days where the flippers physics changes had lost a little bit of that ability for those shots despite all the other gains they made.
As much as i could test for it and did notice it, with all the other settings I had and monitor type, it was still workable for me if I tuned up everything else (USB polling rate, leaf switches, and especially in that my mini-cab HV setup has 120hz, which not only is great for smoother game play / less blur but effectively halves input lag from delayed / buffered frames vs. a 60hz monitor - while vsynced of course). I have another method coming / to be release that has had some discussion here and there on the forums that will save between 10-20 ms of input lag from how currently all VPM table flippers are triggered. It is done by bypassing waiting for VPinMAME to return the solenoid firing status and instead rotates / fires the flippers directly from the keydown / button presses. The previous problems with that is that flippers always stay active but with a certain genre of tables you can leverage other solenoid calls to cease the flippers when appropriate yet gain this more direct fired approach and I have successfully tested a workaround subroutine that will allow a method to work on tables that don't even have the typical "game active" / "game on" status that will allow for this as well plus give the added benefit of being able to more adequately mimic a tilt event using the same synthetic "game on" status derivation / calculation.
I will demonstrate the simpler / more basic of the method in both of the first 2 tables for VPX when I finally get them launched, which will hopefully be soon (Firepower and Comet). The latter method will be for more modern tables like LW3 and AFM and requires a bit more testing but does look promising and will help yield another way we can code to minimize input lag at least within the software layer for VP / VPM.
Edited by jimmyfingers, 04 May 2016 - 10:51 PM.