For those who like the shape and minimalist look of the SLR but perhaps need a little bit more padding under the rear end the XP could be the answer.
The XP shares the sleek lines and ergo shape of the standard SLR, but has padding all over the carbon shell of the saddle, giving a more cushioned ride with only an extra 30g added in weight.
At AW we have found the XP to be very comfortable version of the SLR (if your rear end is the correct shape) and the extra padding is noticeable making it very good for those who don't ride their bike all the time but are perhaps training for a sportive event.
The extra padding on the saddle's peak can also be very beneficial in timetrial or teiathlon situations where the use of aero bars alters your saddle position.