The JBL 4367 is a passive two-way (15" woofer and 1.4" throat horn) with a crossover at 700 Hz.
Imo it’s a good idea to cover the range from about 1 kHz on up with a single driver, and crossing over a bit lower than that would be even better as long as there are no unacceptable consequences, such as significantly reduced pattern control and/or power handing.
I’ve covered the region from about 750 Hz on up with a single compression driver in custom studio monitors, but have not yet done so in anything that I have in production.
Duke