There are too many much more influential factors in ball motion to worry about which ball in your bag has more bottom weight, unless you're bowling with all 3 piece pancake bowling balls. Surface response to the lane surface, core dynamics, layout and how soon it will transition while it is rolling down the lane, proper lane play... Heck, I think the right interchangeable sole and heel combo is more important than bottom weight.
Also, if you're going to think that bottom weight is going to save you sometime, you could, you know, practice on getting the ball into a roll sooner with... Hand positions *gasp*