Ensuite in Attic

Hi,

Just want to get some advice about an ensuite in my attic conversion. I want to get a negative head pump, 3bar so the the presure for shower will be strong but the builder said a normal triton electric shower would work ok.
What i want to know is would i be better off going for the more expensive option of the negative head pump than the triton? I think this will be better option in long run but just want some pro advice..

Thanks,