I prefer not to use 2D waiting. Most of the better partnerships I play in show controls over 2C. I.e. 2♦=0controls 2♥=1control 2♠=2controls 2NT=3controls 3♣=4controls etc. where K=1control and A=2controls. With the hand in question, if partner responds 2♦, showing no A's or K's, you sign off in 3NT as you know that slam has less than 50% chance. If partner responds 2♥, showing one K, you know he has the K of clubs,(the only one missing) and you can investigate a small slam. If partner bids 2♠, showing one ace or two k's, you know he has the A of hearts (the only one missing,he can't have 2 K's)and you will almost surely bid a slam. And if partner bids 2NT, showing an A and a K, or three K's, you know he has both of the missing controls and will probably bid a grand. It seems to me that it is much easier for the big hand to find out a few things about responder's hand than it is for responder to find out lots of things about opener's big hand. The most relevant things for slam bidding are often controls followed by support for a long suit.