I can see me using a 1.4x and 2x converter as part of my regular news kit. Currently I use 10-24, 16-55 and 50-140. Add both converters and that gives me a pretty light, everyday kit that covers 15-420mm (135 equiv). I flex that kit, I often drop the 10-24, especially outdoors, and perhaps add the 35mm f1.4 and/or the 56mm f1.2 depending on what I am expecting to do.
I have to add in a laptop as well if I am away from a vehicle. Currently use with an X-T1, I will go with two X-T2 when (if) they are announced this summer, (I am without a backup body, just sold my X -E1, but I may trade a Canon lens for an X-E2 to tide me over)
Could never have carried the Canon equivalent, not for long anyway.
Martin