aka the previous stable version. 2.7 and 2.9 are dev branches, as will 2.11 be. 2.8 was only released in May last year, which is a little over halfway through the Ubuntu release cycle. It's probably safe to expect it in April's release.
For years, testing has been the defacto 'stable' distribution for anyone who wanted something remotely current and quite stable. Debian 'unstable' is the true testing branch, where bugs can actually impact a user.
Going back to 2000, Debian's stable releases have emerged about once every 2.1 years (median 1.9) [0]. Unless you're hosting a server, the continuously-updated 'testing' branch is the place to be for stable and modern software. I haven't experienced an important 'testing' bug in perhaps at least 7 years.
