hi both, if i can come into the conversation, i have the feeling there's a "3rd wave of ska" in the 90's, taht's the revival we're in, and it's true some of the bands inside are just rock-punky bands with a saxophone; especially in France where i'm from there's a revival of reggae ska music at the moment, with several "options", more rock like "La Ruda Salska" and more "Roots" like "Jim Murple Memorial".
For the US part i wouldn't call bands like Slackers and Hepcat "lack depth, feeling and power", even if they cannot be called "first generation" either...
the third wave of Ska is very linked here with all protestation movements, against the war, against globalization, G8, GMO, against Bush... well it's sort of a generation with strong feelings of freedom and what links them is more the claim in lyrics than the roots of Ska, that explains how some bands are called ska for just including a trumpet in the band...
So i'd rather classify the bands by the feeling of ska they have than by year. Lend an ear to "Jim Murple Memorial" and you'll know Rootska's not dead
hope i'm clear, forgive my english as it's not my mother tongue
ChN1