I'm fairly sure we're flying an Il-2 mod, I see no signs of a 'completely new engine'
(This is not a 'negative' post just an observation)
Do you remember in the very early days the developers telling us that they had halted work on the sim because they realised that the coding would be out of date by the time of release (or something) and so they binned the lot and started all over again "from the ground up"? I remember it happening very well.
You have to wonder (a) what it would have been like if they had carried on with what they started with and (b) whether it really was 'new code' or (/conspiracy theory on) they did it in reverse, ditched the new code and tried to modify IL2. (/off).
I don't have the sim and am not passing any judgement.....just going by what I have seen and read. From the videos the FM do look very similar to IL2 to me too.