The question is a bit broad and could cover a large response with respect to the advantage and disadvantage of large vs. small driver.
First I don't think the OP was interested in line array. It's a different class of speakers all together. I think he was referring to for example having 2x7in drivers vs. one large 10in driver. I don't think the reason of using line array is because one needs that many drivers to replace a single 15in. driver. Line array is not meant to compensate for low end response.
In general a large driver will have more bass response but lacking the transient speed of a smaller driver. So what you would do is having two smaller drivers to get the same bass response of a larger driver, but retain the transient of a smaller driver. Also in general, a small mid range driver (2in or 3in) will have better midrange transient speed compared to a 5.5in or 6.5in driver, but the larger midrange driver will have more weight in the lower midrange especially on the male voice reproduction.
Large drivers also have the benefit lower distortion since it does not have to move a lot to generate the same amount of pressure vs. a smaller driver but of course you need to mix and match driver size since there is no single driver that can play the entire freq. range.
First I don't think the OP was interested in line array. It's a different class of speakers all together. I think he was referring to for example having 2x7in drivers vs. one large 10in driver. I don't think the reason of using line array is because one needs that many drivers to replace a single 15in. driver. Line array is not meant to compensate for low end response.
In general a large driver will have more bass response but lacking the transient speed of a smaller driver. So what you would do is having two smaller drivers to get the same bass response of a larger driver, but retain the transient of a smaller driver. Also in general, a small mid range driver (2in or 3in) will have better midrange transient speed compared to a 5.5in or 6.5in driver, but the larger midrange driver will have more weight in the lower midrange especially on the male voice reproduction.
Large drivers also have the benefit lower distortion since it does not have to move a lot to generate the same amount of pressure vs. a smaller driver but of course you need to mix and match driver size since there is no single driver that can play the entire freq. range.