I own the A4050 and the A4039, and am not a small/weak guy (I'm 30 y/o and 230lbs)...and I think the A4050 is just too large of a stand for regular location work. If you had a specific/crazy need, then I can see *maybe* pulling it out...but even then, I'd like go for a hi hi instead.
I do the vast majority of my work on location (check out my work here: www.eyeballimaging.com) and I use the A4039 as my stand for the key light, and lowel grandstands for the rim/background lights (as they usually only have a 7" reflector), and they all work wonderfully.
I promise that keeping one or two sandbags in your car (which will rarely be needed) is much easier than lugging the *giant* stand out everytime. The A4039 usually works without a sandbag with most of my modifiers unless it's extra windy....and when it's extra windy, even an A4050 could be blown over.
Simply put: The A4050 was the first boom stand that I bought, thinking "buy once buy right" and it's one of the rare occasions that I should've gotten the cheaper/smaller option. I have yet to move into a studio (again, vast majority of my work is on-location) but the A4050 has been sitting relatively unused waiting for it's time in a studio. I use my A4039's on every location shoot that I do.