The Marathon has a radically pronounced bend that provides a greater number of hand holds, and due to its flexibility absorbs shock better than most. The 44cm version has an overall width of 43.5cm.
The run of the cable is greater than normal so you'll need a new set of cables if you're fitting them as a course of upgrading. ITM's Kero 3 has a less radical backward bend and comes in at only £43.99. ITM have recently discontinued this bar but it's readily available on plenty of internet sites.