What moot said.  The no-MG option would be nice.  Also, the Bf110's rear ammo takes a while to fire off.  
More weapon and ammo options are a definite PLUS.
I've suggested before a slider type configuration.  Want 43% cannons/MGs/whatever?  Easily asjustable.  Either in percentages or bullet count... would be a great addition.  
The same for fuel selection.  25, 50, 75, and 100% are too large of a "chunk" of fuel.  A slider would be excellent.  Even further customizable individual fuel TANKS.  I would crap my pants twice if this feature was implemented.  I hate waiting to burn the Fuselage tanks in P40s.  C.205 would also benefit.  I'd leave the wing tanks empty and take 100% main/aux instead.