I believe their media/marketing department came up with a clever way to market old technology instead and not as amazing advancements in gaming. Both features arrived disabled by default, if that means anything.
As far as side scrolling, the lack of this function on the Sensei is a negative but I could never find the full package of 2 side buttons, on the fly sensitivity/mouse profile button, side scrolling, decent DPI, braided wire, page up/down buttons, and a company that stands by their product. The Sensei is my personal favorite as it is only lacking the page up/down and side scrolling, has a nice weight and look to it. The adjustable color LED spectrum is pretty flashy but it is much more limited than what it advertises in that regard. The two lights that you are able to change do not match if the same color is chosen with a certain assortment of colors (certain reds, blues, etc.).
I liked the Razer Imperator but it broke too quickly for a gaming mouse from a gamer-first company. The left mouse button wore down at the rubber receiver from a couple months of CS:S and small amounts of CAD work and that particular mouse may have been defective but Razer did not stand by their product and let me down completely.
The legacy MX Revolution was a kick ass mouse but it was wirless and this was several years ago. It broke quickly due to some internal production issue, Logitech did not stand by their product. I would buy another one today for my laptop if it were not a dated, poor performing mouse in comparison to today's standards.
I have used the G500 or 400, not sure which, but it was a great mouse. I did not think it was as comfortable as the Sensei and I am almost positive the G5/400 I used was wireless.