[Tom White]

the thing that puts me off twist locks is that unless each lock is tight, you can't put the next section down because it just rotates in the section below.

You just hold the section below in your hand and twist the upper section.  Haven't you ever used the old Unger Monster aluminium pole (I can't remember it's name); or even the Harris? 

[alanwilson]

yes I have but it means stopping each section about 6 inches before fully retracted to shorten the next section, then once you've done the lot you're left with a pole about 2ft closed length longer than you want.