The S4 series is as heavy as a double edge safety razor. Don't forget that if you use the ambassador discount from SBG you save some money. I have the ATX S4, I think it's worth it, if you like the sport and you like double edge safety razors than you'll probably like the Eclipse. IMO the added heft removes the feeling like you need to bear down to get a closer shave.
Click on store at the top of the page then choose the headblade link then from there find the product(s) you want and the discount will be applied at check out.