well...group age-wise, i think you can lump them in with oldies, LOL. but yeah, i agree, i can never really classify them as sempais because they are around the same age as the new generation. i guess that happens when you debut young. like Morimoto of Hey! Say! JUMP is only gonna be like, 22, when H!S!J is 10 years old.
T&T are definitely sempai status. just because Takizawa & Imai's significant (& significant i mean
HUGE) Junior work makes them sempais by this point, i would think. Takizawa really created the Golden Age of the Johnny's Juniors. too bad once K-T/H!S!J debut, that period ended...