Basically mentioned above, but also the larger driver exhibits less distortion at higher levels.
There should be some videos of a guy testing just this, comparing various driver sizes and building various cabinets sizes to make them equal.
I find slam is generally associated with mid-bass (~60Hz) and above because the wavelength is shorter. Deep bass has a longer wavelength so it’s smooth bass or felt as pressure. Then again it’s relative because Arendal can use an 8" driver and a smaller cabinet to get more slam but sacrificing lower extension.
Generally though you’ll find an 8" driver in a floor standing speaker will be more smooth than a 6.5" driver above 30Hz. That's likely due to a larger cabinet and lower extension design.
With a 60Hz crossover, it’s probably a discussion of preference and there’s no way to really answer which speaker sounds best to you in that range. You also have to factor your preference in the high frequency, which is huge.
Personally for mixed movie / music use in a general living room, I like speakers that offer the most flexibility, which means larger drivers and a bright sound signature.