The infamous Scan-Speak 18w/5535A autosound woofer with carbon fiber cone, the 18w/8546 kevlar cone 7", and a Revelator 5.5" mid/bass.
Out of the three, the 5535A had the best bass. Very clean, and the un-equalized response in my car doors was just about perfect. Output was excellent as well, definitely top of the class although perhaps slightly less than the newer Seas L18/CA18/G18RNX/P. The 8546 suffered in the low end, due to the very low q and the fact that this driver was intended for ported applications. The Revelator had surprisingly good bass for such a small driver, but couldn't keep up with the larger drivers. Also, it's response in my car door required a bit of eq to add some punch and snap. Scan-Speak is known for it's bass, and I have to say all three drivers were at the very top for overall displacement.
Midrange wise, I thought the 8546 was best overall. Clarity was very good, and the Kevlar breakup wasn't so noticeable especially if used below 2khz. The 5535A was dark, and velvety by comparison. Not big on detail, but overly warm and "soft". It didn't confuse details so much as just soften them, and when driven hard it held its composure very well. The revelator on the other hand, is a very wideband driver capable of much greater top end extension than either of the other drivers. Although it didn't have the sheer dynamic, effortless quality of the 8546 or it's raw clarity, it sounded very natural and open in it's presentation. A good balance between the dark tonal qualities of the 5535a, and the lively more detailed presentation of the 8546.
Build quality on all these drivers were superb. Only the revelator however had the new open cast basket with ventilation under the spider. However all 3 drivers had the very low distortion sd-1 motor with dual copper rings.