Don't know about parent poster, but I think:

a) It's better to have it baked into the browser in general, if it's something you use. Worse if it's not, though.

b) Screenshots with selectors are pretty awesome, and I don't think most extensions would provide that

Which extension are your referencing. I'm currently using Page Saver but previously used Awesome Screenshot Plus until they started intercepting pages and spamming adverts to them by default. Having it in-browser is good.

Also I've not seen a screenshot tool that allowed an id to be specified before as someone said this will/does.