First, they make some wonderful packs that adjust to different body types. I am over 6' and have always struggled with huge packs that did not fit. I now have a pack that has a small frame and is bigger than my equally tall boyfriends. I got a pack for solo and group backpacking, so when I go out with other people, I am less full and it cinches down wonderfully and fits well.
The only down side, and this is a big one for me, is that you have to defend your space with spit and vinegar. (spit and camp stove fuel?) Otherwise you will carry the camp stove fuel, along with "one more little thing"....like the tent! If you pack with people who have small packs, they look at all your space as if you are not carrying your share and want to even it out visually, (or they have some item they are having a hard time stuffing and they cannot help but notice how easily it would fit in yours) or out on the trail, they have sore knees (tired feet) and see how you can be so very helpful with just another little thing. I tend to be easygoing....and I tend to feel like a pack animal.