I will agree with you if that is all you really want. When you're finally above 30k in the 110 or 410 and not overladen, it's larger wingspan is its strongest card. Wingspan is the ones thing the A8 is particularly lagging behind on at 27k+ (so is the D9, thus the 152 came along), particularly the subvarient that it is modeled after. Never a 190-A9 around in AH when you need it though, chyaknow.
For being about equal with the 410 at extreme altitudes I think the A8 is still a better choice though - it has better survivability (smaller shape/target, "tougher" than the 410 in many aspects) and can get turned around and repositioned faster at higher speeds (it's a trade off, if you keep your speed up in the A8 and don't force it to turn too hard with it's stuby and heavy wings then all is well, but too much speed in the 410 can be very bad so it forces you to govern the top speed in high-alt slashing attacks. After a pass the 410 is slower than an A8 would be, but it still can turn around and reposition almost as well if not better than the faster A8, but the 410 is now in a slower state/position for pressing the next attack than the A8.
(^ what is BnZ 101)
You claimed the 410 is superior to the A8 due to outpacing it while flying alongside them in the scenario. Charts proove this is only possible above 29.5k with no WEP (and also possible betwen 7.5 and 12.5k with no WEP). 410s also have better internal and external fuel reserves, it was feasable for 410s to take off with enough fuel to fly the entire scenario at full throttle, but the A8s must fly economicaly to loiter long enough.
One of my favorite features of the 410 and 110 in high altitude work is that you dont need an external fuel tank and its penalties to still have a luxurious amount of fuel to work with, nor do you need the heaviest cannon packages to still hot-knife through buffs, all this works in your favor when most other single-engine aircraft will need to slap on extra tanks and drag them around or heavier-than-normal gun and ammo loadouts to meet their high-altitude and long-duration (buff escort) or heavy-hitting (buff interception) needs.
I personally feel the 410 is equal at high-altitude buff interception work with the 190-A8 on a performance level, in AH. If AH had an A9 or one of the dozen-other 190 A8 varients that Germany produced, then I suspect the 410 would take a place behind them in performance.... a place that the 410 historicaly did find itself in during WWII.