More load to CPU and MB NB (USB-controller), possible shortening USB lifespan, more chance of not being stable. It also feels like I'm "playing from underwater" ingame (monitor is capable of 160 Hz, so that's not the issue). While on the pragmatical side of things, it's only -1 ms compared to 500, which is basically irrelevant.
I found many statements on different hardware forums, etc people claiming that all these consequences you just threw in are as irrelevant as either using one or another today in 2014.
About your last part, also from many reports, it has been concluded a long time ago already that you don't measure lag with each component separated (or you do but wait), lag is measured while playing video games seriously overall that way: mice + kb + monitor + internet + reaction time (subject) + etc = better idea of lag. If 1 ms is not significant, look again at it after doing the math with the rest, and if each time you pick one component and think "1 ms is nothing", then when you do the math you don't lose 1 ms overall... you lose 4, 5, maybe 10, maybe 20... a bit exaggerated but you got the idea ^_^.
Let's see that bad feeling, similar to lag;
Mice: Razer Salmosa, 800 cpi / SS Kinzu v1, 800 cpi / MX 300 / MX 500/ IME 3.0 / WMO / Diamondback / Diamondback 3G / Abyssus, accelfix, Win 6/11, EPP off
KB: IBM SK-8820, PS/2, juuuust fine
monitor: DELL P1130 / Dell P992 / Eizo FlexScan F931, CRT, 640 x 480 @ 120 Hz
internet: 5 mbit ADSL, but irrelevant, because it's the same with practice mode
reaction time: that's really not bad :>
So that 1 ms between 500 and 1000 Hz is irrelevant.
And as you said, even today in 2014, small things racks up. :>
If you have a recent CPU/MB 1000hz isn't gonna do anything, CPC in France are doing power consumption tests and stressing hardwares etc guys over there always said this is not even a problem nowadays, this is why I said "today in 2014". If this was such a big issue I'm sure the RMA rates on MB would be higher and the reasons would be because "USB ports are dead due to X reasons related too high frequencies": but it is NOT.
I am sure you think "Oh this guy is here to say that 500hz is shit", I'm not, you read it wrong, use anything you want, but don't say that 1000hz is bad today, back then the RMA rate for MBs wasn't even an issue afaik, if it was, I would be glad to read about it with some sources from the manufacturers.
And again, your example doesn't mean anything about what I've said before, if you want to compare 1 ms for ONE component then obviously it is irrelevant, but if you want to compare it overall with different components, like some people do "Well 60hz is ok, that screen with 15 ms response time will be good don't worry, it's ok too if I play with 100 ms don't worry, oh I'm sure I will be ok etc" then lag starts being an issue, I'm going to try to find that guy who wrote an article about it, you will understand what I'm talking about...
an another topic, do you have more control(visible control instead of pixel skipping) with minor adjustments on higher dpi than 400?? just wondering if high dpi really have an application?
My answer and opinion would be no, it's the same. Then it depends on the games. But on QL I think you don't have more control. But I prefer to adjust everything from a low/medium dpi, than a very high dpi. Each to their own...
higher dpi prevents pixelskipping if u want to have high cursor speed(high sens).
so you can use a ingame sens which doesn't skip pixels, but use high DPI on the mosue to have a high mousespeed anyways.
I have tested this. And yes you can get more control with over 400 dpi. The thing is this really only applies to very very small movements and if you have a low sensitivity then there is no benefit from going higher than 400dpi. Unless your using a crazy high sensitivity like 20 or 30 (at 400dpi) there is absolutely no benefit going over 800dpi.
i notice a bit of skipping with 14cm/360 with only 400dpi, and ALOT on other games where i started using pretty high since aiming is not that important when playing SP fps games(im lazy). At 8cm it's skipping about 5pixels minimum.