I'm getting an improve of 0.0027 blending my individual models. 

I think scores in the 44s  will need models under .453 or blending improve in the 0.0050 range or probably both. 

How much are you getting with the blending? 

I've only managed to achieve a 0.001 improvement from my best single model, by blending with other (alone inferior) models. I've only ever tried to blend three models at once, however, and I manually chose the coefficients... this is on my list of things to improve. :-)