Neat little idea

You are dealt ♠xxx ♥Ax ♦10xx ♣AKxxx.

Partner opens 1♥, and you respond a forcing 1NT. Partner rebids 2♦. Now what?

At the table, the Responder with this hand in the story I saw responded 2♥, a practical call. After Opener rebid 3♦, Responder found a nice 4♠ call, a "Bluhmer," showing this type of hand. A "Bluhmer" is a specific instance of an Empathetic Splinter that is the easy kind, in that the empathizing of the stiff is rather easy when partner bids around it.

Nice auction. However, Ken Eichenbaum suggested a better auction, IMO.

The thought goes along logical lines. We all know about the "Impossible 2♠" call, when a Responder who bids a forcing 1NT in response to a heart opening later bids 2♠ to show extras and support for Opener's indicated minor. This makes a lot of sense, especially when the minor is clubs (a suit that is more and more suspect with 2/1 sequences like this, as people often promise four diamonds here and might even have a stiff club with 4531 shape). Bart in the club sequence also helps.

However, in the diamonds-rebid situation, especially with the "real diamonds" crowd, the concern is lessened. It seems reasonable that a greater concern in this situation is the situation where Responder would have made a simple 2♣ response playing SAYC but was forced to bid 1NT forcing because of 2/1 GF, now preempted out of showing the clubs.

Eichenbaum suggested that this 2♠ call, after a 2♦ rebid by Opener, would be more effective as a sort of "snapdragon" type of call -- clubs, heart tolerance, maximum (good enough for a 2/1 in SAYC, maybe). I like this.

With the actual hand, this takes a lot of pressure off of Opener to come up with that 3♣ call. In practice, 3♣ would now only be placing the contract. Opener, however, had such a great hand that he would likely bid toward slam at this point. His hand was ♠A ♥KJ10xx ♦AKJx ♣Qxx.

More interesting, perhaps, is if Opener had held a lesser hand, like ♠x ♥KJ10xx ♦AKxx ♣Qxx or ♠A ♥KQJxx ♦Axxx ♣Qxx. With either of these, the auction after the 2♥ practical rebid by Responder would likely die. However, game in either hearts or clubs is fairly good if Opener knows that Responder's usual "look" is ♥Hx/♣HHxxx. Heck, on that second one, 6♥ or 6♣ seems odds-on to make.

Note, by the way, that the auctions 1♥-P-1NT!-P-2♦-P-2♠!-P-3♣/4♣ both seem to promise a stiff spade, such that there is no need for any sort of 4♠ "splinter" or even a 3♠ "splinter without the jump." It might make more sense for 3♠ to be some sort of game choice bid and for 4♠ to be immediate Exclusion RKCB, or something like that.