Then you completely missed the point of my post.
I added another one

As for performance the Spitfire I to XVI goes from 312 mph at SL to 344 mph. An increase of 10.2%.
The He 111 H1-H4 to H-16 would go from 221 as SL to about 244 mph. An increase of 10.4%.
A He 111H-16 would be almost as fast as a Ju-88 at 20K.
In other words: Still dead meat on the table. This speed improvement will just barely change the survival chances on it's own.
You can't just measure speed differences in simple percentages... you also have to consider about which speed range we are talking. The Spi I is much slower than about every other fighter it will encounter, the 16 not anymore. The 111 H-16 will still be slow, even with 10% more top speed.
The performance improvement for Spit I->XVI in top speed, rate of roll armament and climb rate make all the difference between a death trap (in LW arena context) that can hardly can get a kill (again in overall MA context) and a stellar, very powerful fighter that received "perk it" cries more than any other ride in the past.
A HE 111 that's "almost as fast" as a Ju 88 and still has limited (yet improved armament) will still be a quite underperforming bomber in the arena.
So yes, the difference between Spit 1 & 16 and He 111 H-6 and H-16 are indeed worlds apart.