are the slats of any use to turn better with the 109
 

ive seen 109 doing bat turns :)

do they use slats or whats the trick?

If you are at the optimal turnspeed and lower the flaps just a little while the slats pop, you can make a very nice turn. But it bleeds like a mofo.

there is not really any control you have on when the slats pop. I once tried to have em pop and i had to fly REALLY slow to make em come out. Much too slow for a dogfight. The 109 performs much better at higher speeds. Turning is what spits do better. I think no slats or flaps will change that.

Winger

totally agreed:-)
i'm flying the 109's online most of the time keep the speed about 350-400 klm and will get good tight turns...but beware cause the speed bleeds very quickly
the slats will be engaged at about 200 klm in a very tight turn to prevent the stall a little more:-)

As lacking in detail as the FM on this game still is, I never use a hard turn unless I am 100% positive that it'll park me nicely on someone's six.

Airspeed isn't what works the Handley Page slats, it's the Angle of Attack, so they should pop out at high speed IF you can pull the appropriate G (G being indicative of AoA, of course).

The AI cheat.

Well, you won't get very high AoA if you go fast.

Agreed