I saw an article that showed the sound output of the 518 vs the 558 and 598. I was amazed to see that the sound signature for each headphone was practically identical. So I decided to take a shot a but a pair. I have NOT been disappointed.
 
Comparing the three headphone for myself I can tell you they all share a very similar sound. The HD 518 have a slightly stronger bass, the 558 a bit more highs and the 598 a bit more neutral of the three. As a gamer the extra bass is welcome to my gaming experience and I find I personally prefer the sound of the 518.
 
The open back, teamed with solid bass results in an incredible PC Gaming experience. The reasonable pricing means these are easily within reach of any gamer. They are not the most comfortable of the three mentioned but they are still a very comfortable headphone, I easily can wear these and have for long gaming sessions. Connect these to a good gaming sound source and you have a great product at a great price for a great experience.

With the revolve Kingston stepped away from the great design of the original Clouds and decided to go in a new (more gamey) design direction. According to my source at Kingston one of the goals was to open up the sound stage more, something closer to open back in effect.
 
I was initially impressed with the comfort of the Revolver design. It felt good on my head, seeming to sit a bit lighter than the Cloud. Not a big fan of the mic and arm placement but it was not the worst I have ever used. The look of the Revolver to me was a turn off but again this is a personal choice.
 
When I used the headset I was impressed with the more open sound stage and the sound over all. It was very similar to my Cloud experience with a more open sound stage. That was until I moved my head quickly.
 
The design of the headband and the way it attaches to the cans creates a real issue. When you head is moved quickly or you bump the headphone a ring resonates within the sound stage. The ring is audible over all volumes of sound and I have found no way to stop it. This to me is extremely distracting and ruins what is otherwise a good headset.  As a gamer I still find the original Clouds to be the best headset Kingston has produced and one of the best you can buy.
 
I suggest people looking for a good gaming headset pass on the Revolver. They are not awful but for less money you can buy a better gaming experience with the original Cloud design.  The headset is solid if you never move your head or do not have people around you like at a LAN event.