I think its more of a problem anytime when one brand comments on another brand's product. Its just in very bad taste and appears a little deperate to control the perception. Plus, in being part of the forums for years now I have found that one brand knows very little about the other brands product and what actually makes it tick.
The effective piston diameter of speaker is measured from the very center of the surround to surround. Then this is converted to a surface area via a simple formula.
I can confirm that the Exile XM9 has an outer diameter of an additional 3/8" over the Wetsounds REV8. This equates to 12 percent more surface area which might translate to as much as a 0.3 dB increase in output. Now a difference of 1.0 dB is the minimum that a human can discern in an ideal 'quiet' room let alone an environment that is windy and filled with ambient noise. So once this difference is actually put into context you can better judge whether that fine of a distinction makes a difference or not. Personally I wouldn't exactly hang my hat on it.

Earmark Marine