First, I do not think a perk price is justified. Fighting vs a single Wirbel only needs a change of player tactics. It's too vulnerable to justify any perking. Sure it will be the most used AA vehicle by a big margin, but that alone isn't enough - Due to that logic, Ostwind would had to be perked long ago when almost no one upped a M16.
However, it is much more capable vs fighters and enemy towns, so having the same 25 ENY as the Ostwind is just not right
Actually, I think the biggest impact on gameplay is currently still going onder the radar of most players. It's (as I already pointed) out its efficency as a very efficient horde tool vs enemy towns. I did a few tests and computations:
The Wirbelwind is 3 times more powerful vs towns than the Ostwind!
A Ostwind does the equivalent to 39lbs of ordonance vs structures per second (2.5 rounds à 15.6lbs)
A Wirbelwind does the equivalent of 120lbs per second! (30 rounds à 4lbs)
Where 2 Ostwinds would in theory need 3.89 mins to take down all 56 buildings of a town, two Wirbelwinds can do the same in 1.29mins.
(Practical numbers are somewhat higher in both cases, but the ratio is still the same)
A few squads (the usual suspects of course 
) have already noted this and started to do some very quick gv rushes on enemy bases. When a town is far away enough from the airfield so that the base alarm doesn't go off, it's often impossible to spot & stop these sneak attacks before it's over. In fact, they are much more effective than those so dreaded NOE basegrab missions.
Therefore, it is my opinion and humble wish, that due to it's better overall performance, the WW ENY value is lowered to 15. When numbers get unbalanced, it should fall under the same restrictions as Typhoons, 110G's, N1Ks or 190Ds
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(Of course HTC could just adjust ROF restrictions or turret rotation speed in accordance to real life numbers and leave ENY at 25 )
I agree with most of what you said here. However, regarding people not noticing that only a town is flashing, I would dispute you about that. Good players pay attention to such details. So if you are up against any sort of decent opposition, it is definitely going to be noticed, and not overlooked as you imply. And since Wirbelwinds only go 25mph, there is still plenty of time to up defense to intercept them before they reach the town.
So even though I am a LTAR, I would say that a well run NOE base grab using bombers for the town is still the fastest way to take down a town and capture a base, from a practical standpoint. Pulling that off takes real organization and teamwork, though. Three decent buff pilots can down a town in a single pass. All the fighters in the mission can then intercept any uppers from the field and act as a buffer, while the troops are brought in.
The turret rotation speed on the Wirbel is better than what the Osti has, and probably not realistic. However, I cannot support any negative changes to the Wirbelwind, as doing that would be heresy for any LTAR to do.
And I do not wish to be excommunicated.
