Wow all the OP wants is pump suggestions stated he wasn't looking for conservation idea's.
OP, same as you, if I am taking a shower and the wife is doing dishes I want the same pressure and not burned. I switched my OEM pump for this one http://www.amazon.com/FloJet-04325143A-Pressure-4-5-GPM-12-Volt/dp/B000O8F1SY/ref=sr_1_10?ie=UTF8&qid=1458847824&sr=8-10&keywords=flojet+water+pump
It was my first upgrade when I bought the new TT and I had the same one in my old TT. It ramps up on speed to meet the demand. It is only 40 PSI but seems to be all that is needs because the flow to devices (all turned on) are the same if I am on pump or city.