Okay... 2-ways have some inherent compromise re: mid-bass size. You either get good midrange behavior or low end performance but rarely both.
Smaller mid-bass drivers generally let you cross over a bit higher before a severe directivity mismatch sans waveguides which generally improves tweeter distortion figures, but they don't extend as low (somewhat dependent on cabinet design) and their bass distortion performance is not great at high SPLs, even when crossed over with a sub or 2. Plus, given their smaller area, they're not going to be quite so punchy as a larger driver. Larger drivers extend lower, have much greater surface area, and behave better re: bass distortion, but like you'd expect they start to beam lower meaning for good dispersion you have to cross the tweeter over lower which can (if not designed carefully) end up increasing tweeter distortion.
A sub can help with smaller 2-way midbass drivers, but IMO, 3-ways with a dedicated low driver is just a better solution in general. An 8" woofer plus 3-4" mid driver crossed over around 300-500Hz is just plain going to work better than an 8" mid-bass crossed over with a 1" tweeter at like 2KHz.
I feel that we should add an asterisk here with this one... This is the distortion vs frequency plot from the 308P, which has the larger woofer and should perform better at low frequencies (all others being equal). It's very likely the 305P performs
quite a bit worse re: LF distortion.