Hi oks81,
I would not compare TAD 4" diaphragm driver with JBL 244x loaded with Be (Truext) diaphragm, may be with 476Be only would comparable, but if 2405 is applied, I think that JBL SL diaphragm would be acceptable solution too, as it is not 'ringing' over 10kHz.
Using JBL 4" AL diaphragm (2441) under 800Hz have to be done with more care, especially if not too steep HF network is applied. May be even 2445 Ti diaphragm is not so bad solution too.
regards
ivica
H