My brick-and-mortar music store had only 0.60 an 1.0 Ultex bass picks so I ordered the 0.73 and the 0.88 to make a complete comparison. For a long time I used only the 0.60 because it seemed to pull more harmonics when I played unplugged, but that's a bad habit.
The more acute sound seems to be easier to hear unplugged but it's also a little rubbery, and when I adjust the string height I raise them to the point the string doesn't sound rubbery. So the pick shouldn't make it sound rubbery either, and it takes a harder pick to achieve that. The 0.73 isn't hard enough for my taste but I'm glad I bought it to make the experiment.
Now I'll play only the 1.0 and maybe the 1.14 that I will try next time I order stuff from Thomann. With the 0.60, 0.73, 0.88 and 1.0 at hand for immediate comparison I also noted the harder picks don't stay as long on the string because they don't flex, so no time is wasted. And they don't waste motion energy either, because when a softer pick bends, the energy used to bend it is not there to push the string anymore.
The impression that thicker picks give out less high harmonics is not a problem, they pull more bass, and the difference is easlily adjusted with the low/mid/high knobs on the amp.