The longest we have spent living out of a carry-on has been about three months. The benefits definitely outweighed the negatives. If we ran out of clothes, we could often find laundry facilities. Anything we forgot could usually be bought locally. So, for this trip we took the plunge and aimed to pack only a carry-on for seven months of travel.
It’s easier to pack for seven months in a carry-on when you’re travelling during summer. No hats, scarves, gloves, or bulky coats are necessary. Of course, when we make it back to the East Coast it will be autumn and may be a little chilly. At that point, we can easily buy warmer clothes (as Hampton pointed out, clothes tend to be more expensive in Europe).