I personally only have hands-on experience with SaberForge champion sabers.
The champion hilts currently utilize the SaberCore soundboard, which comes in several different varieties each with their own unique auxiliary sound effect that you can activate by pressing the AV switch when the saber is powered on. The SaberCore Viridian has the same basic sounds as the old Champion level Neutrino soundboard (which is no longer available), and is generally considered a "light side" sound font. It's auxiliary sound effect is a blaster bolt deflection sound. The SaberCore Crimson is brand new, Phil who owns SaberForge just finished adding the option into the order menus for all his champion hilts. This is a much darker sound font and is great for Sith. The auxiliary effect is Force lightning deflection, I believe. Phil will be posting a video review sometime this weekend, stay tuned to the SaberForge Facebook page and this forum for news. My understanding is that a couple additional SaberCore soundboards will be available in the coming months as well, each with a different auxiliary effect and possibly different general sound fonts as well. All of the champion SaberCore soundboards can power the standard 6W LED or the 12W LED (for an additional $30 during checkout).
The Hero sabers have the ability to have two 6W LEDs that you can switch between just with a flick of the wrist while holding the saber, and then you can also blend those two colors together into a single 12W color (for example, if you had a 6W blue and a 6W red, your 12W would be purple). The Hero soundboard also features 5 different sound fonts which are customizable. This is a big improvement over the Champion level SaberCore, which comes preprogrammed with a sound font and cannot be changed. The Hero soundboard has a microSD card that you can plug into the computer and customize all the sounds to your liking. It also features flash on clash and a bunch of other features that I don't really know about, never actually having played with one myself.
I really have no desire for multiple colors or different sound fonts, so I personally don't feel the need to spend the extra money to go from a champion to a hero. But many people think it is well worth the extra money, and they are quite happy with their Hero edition sabers. There are a couple of threads on this forum about the Hero, I'd recommend checking them out for more information and reviews from other users.
In terms of AV switches, the Champions have 1 AV switch and the Hero sabers have 2, again because the Hero has so many more features than the Champion. But for me, all those extra features of the Hero are just a lot of icing on the already delicious cake that is the Champion. So I don't think I'll be getting a Hero any time soon, but who knows? Things may change