If those are really the choices I would go for the Beta LT if you like pit zips. I know a lot of people don't care for them, but if you like them I say keep them.
I just got rid of a Polartec Neoshell jacket because the Alpha SL pullover had better pit zips. For me when moving hard, the good pit zips make a significant difference in how I feel. I just don't think I can dump as much heat through the albeit very breathable fabric as I can through these very well shaped holes under my arm (the Arc'teryx pit zips or cut of the jacket under the arm did make a big difference compared to other jackets with smaller pit zips and tighter cut).
With the Beta LT Hybrid you would get a LT jacket, which might be a bit more robust, with pit zips for the extra 20gr. Not a bad deal weight wise.
As an aside if they really got rid of the pit zips under the Alpha SL, Alpha SL hybrid and Alpha SL pullover than that would be, sad.