thats a good question !
I hardly hear of anyone on here using modular poles anymore.
I guess its because since Gardiners and others upped their game with innovative and lighter user friendly telescopics , for most there is no need for them.
Personally I cannot speak for gardiners modular, but I did own an emporium modular pole 40ft.
I did'nt get on with it, sections stuck together (can be overcome with adding a buffer of electrical tape) and eventually sections got chipped and cracked , even had a section snap - but that was more to do with quality.
I suppose they have a place, stiffer and lighter than telescopics, but a bit of a faff to set up and take down and put away, on a long run of windows at height on a commercial job they probably work well.
But if using for domestics and lots of different heights then telescopic carbon rules!, so much more versatile and user friendly.
I have a supermax 40, but if needed I'd happily go to a supermax 50, any higher I'd then maybe think about modular, but I don't ever expect to need to go that high and the price would not justify it for the odd job or two.
Simon