I had a Sigma 530 Super for awhile. The 610 super looks to be the same except for the power. It has more features than the 430EX II because it will also act a a Canon ETTL Master or Slave and also has a basic optical slave mode which can be handy.
The optical slave won't work with your XS camera though because the XS flash always fires an ETTL preflash which will cause the Sigma to fire too soon. The Sigma is also not compatible with the Canon in-camera flash menu.
In your case, unless you buy a second flash, you will not be able to use the extra features, and you lose the in-camera flash menu. All you are getting is a little extra power.
You should try it out for awhile to see if that extra power is really important for you. You will also notice that the build quality is not as good as the Canon.
