Ditto. One of my fave basses, the ATK is 5.22kg and one of my SR 6 strings, just on 5kg. I haven't played a 4 hour set in ages, but I have stood practicing and writing with both on a strap for that long.
No, as I still have a 1x15 and a 2x15 from the 80s and 70s respectively, but I like the ease of air movement that larger drivers have. I agree with the earlier comments about dispersion, but for 40y I've gotten around that with multi way cabs as I've preferred a clean wideband speaker that I can EQ to my tastes, not just having it baked in and smothering like an old Ampeg. These days with multiFX and modellers, I can make my cabs sound like just about anything, good enough for me and anyone else except for maybe the one old tone cork sniffer I might run into every few years.
The cab currently under construction is a 15 + 8 coax, in 2 boxes so it will fit into the back of my sedan. This adds a little weight to the total, but it's 2 smaller boxes so each are easier to manhandle and the coax can be raised on a stick to ear height. I designed it for what I wanted as there aren't any commercial boxes available, new or S/H that do what I want.