OK... another thing I just got a handle on. Looking back in this thread you will see that I currently have THREE different slides.
The Bluesbottle
A glass Steve Clayton and a brass Jim Dunlop
The Bluesbottle has a 30mm diameter, that gives a circumference of 94.25mm
The other two have a 28mm diameter, thus a a circumference of 87.97 mm.
The greater circumference and the of the Bluebottle does, I think, make for better control in terms of downward pressure, but it also means a flatter radius on the outside of the slide and I am finding that makes it harder to get into position accurately. You have to have the slide RIGHT OVER the fret to get an accurate note (at least down the low end of the note) and this precise positioning is made a little more difficult with the larger diameter slide.
Trade offs and more trade offs....