Does anyone have knowledge re: the effectiveness of these 2 temp control systems for Delta showerheads? They both say they limit the water temp to a variance of +/- 3* but that the "Tempassure" actually monitors the temp. and is therefore more effective than the pressure balance system (Scald Guard). Also, the hi temp limiter on the tempassure doesn't need seasonal adjustment. This all according to Delta's website. Since the average price diff. between the 2 for any given model is $172 I'm trying to understand if the temp variance is +/- 3* on both systems, does the extra $172 really get you better performance? Thanks in advance if anyone has a clue on this.