The 109 does seem just as spin-heavy as the Spit or Hurricane in CloD, which does a bit weird indeed.

I think the slats controls that some people are referring too are for the Tiger Moth. That has manually adjustable slats, whereas the Bf109s are automatic AFAIK... not sure about the bf110 but i would imagine they are automatic as well.

As for the actual flight models I wouldn't know TBH, havent flown them enough yet.

That could be a indication that the slats are working as they should!
With the higher wing-load of the bf109 the plane should have more trouble with stalls.
Not more trouble -> slats are working, thats what i think.