r_s_dhar,
I haven't ready any of Novak's work, sorry. Basically, box ratios are based on Qts, Vas and Fs.
Again, those ratios are just a set of countless possible ratios. Really, there's no need to be overly critical of ratios, your design goals, driver details and listening room dictate the size and position of the box [in your listening room]. You'd only look up tables to start you off in the design process or if you don't have a way of using simulation software.
If you'd like to keep group-delay down and transient response acceptable, try to come up with a transfer function that doesn't suddenly "bend." A gradual bend from the passband to the transition band of the transfer function gives good results.
Your room's acoustics will seriously dwarf any slight difference your candidate box may have with the optimal box.