I don't think that's necessary. At that point "Quick Reply" would be a total misnomer, and it never worked that way before, anyway. I think there are better uses of time than writing completely new functionality for something which is easily accessible two other ways already.
At least, I think, you should make it so that "Go Advanced" incorporates the multi-quote function, because if I remember correctly, IT DID on the old layout. I didn't think to click the "Reply w/Quote" icon. I don't really like that -- I always use "Go Advanced." And the "Post Reply" button is way at the top. You have to scroll up to go there. That's a lengthy road trip to scroll up -- it could take up to two or three seconds of valuable, never-to-be-returned-to-you time.