Pusher fans and puller fans of the same geometry will move similar amounts of air through the radiator, however:
-the pusher is pushing engine-hot air through the radiator so your low temp threshold is higher.
-the puller is also blowing air along the engine which has a bit of a cooling effect as well.
I'd imagine changing to a pusher fan and adding a shroud to get more efficient air movement might improve the overall effect. Personally, I'm considering making air shutters to mount on the footpegs that could be used to deflect hot air in the summer and direct hot air into the operator in the winter.
my $.02 I am not an engineer, nor do I play one on TV...