There are a lot of variables there... What size batches are you doing currently, what burner, etc. As for the electric side of things, how much power do you have access to (i.e. 240v, how many amps), what size elements are you considering?
Personally, I have a 240v/30amp Kal clone with 5500w camco ripple elements in both my hlt and bk. I believe there are threads providing the amount of time it should take to heat a given amount of water and the electrical consumption, but I can't find them at the moment. I can tell you that it is substantially faster. Further, I have not noticed any changes in my electrical bill and I brew almost weekly.