We shouldn't forget that they respond to attacks... The ability disappears... I'm just on my phone, so I'll answer everything when I get to my computer...

I'm not trying to prove that Temptresses are better than Demonesses, and I never have. The choice of which unit to upgrade depends on many circumstances, as their purpose is quite different. And Demons themselves can perfectly manage without ranged units; just give them tactics and/or +1 to speed, and most of the army will reach the target. I'm just trying to prove that Temptresses are a very good upgrade, which, sometimes, can even bring more benefit than Demonesses. But in some situations, the hypnosis of Temptresses makes them a very attractive target, just like Elven Archers, area-of-effect spells from Warlocks, dark magic, etc. In these cases, Demonesses might bring more benefit. Although, it's not a given that the opponent will choose Temptresses specifically, as there are other options :)