Gadget of the day: Roman Key Card Blackwood

Here's another one. I for one know that I haven't been bidding slam nearly often enough, so pardon me while I try to rectify that a bit. We all know classic Blackwood, the 4NT slambound bid that asks partner about aces (what the Germans call Assfrage). In Roman Key Card Blackwood (named for the Italian bridge team that used it to win embarrassingly many international tournaments in the '60s), the 4NT bid after determining a trump fit asks not just about aces but about the five key cards, namely the aces plus the king of trump. This approach gives a more accurate sense of how high to bid the contract. So, as I learned it, responses to 4NT in RKCB go like this:

5C: 0 or 3 of the 5 key cards
5D: 1 or 4 key cards
5H: 2 or 5 key cards and not the queen of trump
5S: 2 or 5 key cards with the queen of trump

There are some possible additional steps after that, but methods vary so perhaps let's take it slow for now. What do you think?