I like it a lot better as a player when I get a single plane and single history that is my role in the scenario.
If it's a collection of planes, it seems a lot more shallow to me and gets to be more like a board game with no scenario depth.
One one extreme, you'd sign up for a scenario and be in JG 52, where Hartman, Krupinski, Rall, and Barkhorn flew. You'd fly a 109G on the Eastern Front. If you want, you can fly the 109G for the month in advance of the scenario and get all the nuances of it. If you are really into it, you could read a book that has some JG 52 action in it.
On the other extreme, your side gets 109G's, 190A's, 190F's, Ju 87's, and Ju 88's, and you get shuffled temporarily into whichever one seems best for some points formula or to meet (somewhat-artificial) objective X. People in those situations don't bother to practice the various aircraft, get into the history of it, or read about a particular group. They just show up on game day and fly whatever and with whatever is their current AH ability. That, to me, biases things away from what makes scenarios toward an event that becomes more like "This Day" or a snapshot.
So, if I think particular groups will work, I am heavily in favor of that.
Only if I think being in a particular group will be a disaster do I use the tool of lumping that ride in with others, to dilute the downside of it.
In this scenario, 190F-8's should be fine. If a side has a problem utilizing 190F-8's when historically it would have Stukas, I have no sympathy.
Il-2's, I *think* will be OK. In fact, while I have been for a long time wishing for an Eastern Front scenario so that I could fly the P-39 in it, now that it's here, the Il-2 is looking also appealing to me. The Il-2 is such a major aircraft of WWII. The Tu-2's also look appealing.
It is interesting to discuss all of this, though. I like discussions.