Okay, the water heater answered my question. It toggled down to the bottom element. Seems that the bottom element makes noise and the top one does not. That doesn't mean anything right?
My main question is still unanswered though; why does my brand new water heater perform so much worse than my 16 year old one (except for the leaking)? One theory I had is that new models don't go up as high in temperature and mark a different spot as normal. This one goes 90-150 with 120 marked as normal. Maybe my other one went way hotter and had some other spot normal, so I had it making 150 degree water and everything seemed great? This would be consistent with the fact that I seem to be keeping the shower set to a hotter setting now than before. I know I didn't have the old one maxed out.