The benefits of going seamless
Seamless gutters are superior to their sectional counterparts because they minimize leaks. Even well-constructed seams with ample sealant can start to wear away over time, allowing water to escape the gutter system.
Seams also form ridges along the bottom of the gutter, backing up small amounts of water and giving debris plenty of opportunity to form a blockage. Seamless gutters avoid this problem altogether, making them much easier to clean. Since they’re formed from a single sheet of metal, seamless gutters have a more uniform look than sectional pieces.
Source: Angies List