The Duke is adjustable. The S goes from 265 to 320. You want to get the smallest that fits your bootsole as they end up being stiffer that way. My boot sole is 305ish.
Price wize, ski was $450 pro form, $309 binding, plus mount and tax, so I have around $800 in em from 3 weeks ago, so this seems a pretty good deal. I'd also sell ski only and keep the duke as they arent' so easy to find pro deals on.