The other night, a friend of mine and I, who do not play all that frequently, had an auction where one of us forgot whether we played RONF or new suits non-forcing after a two-level weak opening. The specific auction was 2H-P-2S-P-? Opener opted to show secondary diamonds, feeling that the auction was forcing and that, without discussion otherwise, a diamond call should show diamonds. Responder, thinking that 2S was non-forcing, logically construed 3D as agreeing spades and showing extras, perhaps a feature, perhaps shortness. Needless to say, the auction got a tad out of control.
This then caused an initial discussion of "what do we play?" Looking at the convention card resolved that.
The secondary discussion, then, was "why do we play that?" This resulted in a debate as to the merits of escape calls and of constructive calls with stronger hands.
It then dawned on me that perhaps a new style of responding might be worth considering. Responding methods are often easiest to remember if they parallel other structures for other sequences. This actually made for a relatively easy method.
After 2H, 2S by Responder is a relay call, showing one or both minors. This parallels our 2S response to a 1NT opening. Opener picks the minor of preference (bidding 2NT with diamond preference, to get under 3C). After this, Responder can then pass 3C to play, convert 2NT to 3C to play, or bid 3D to play, all of which cater to either one-suited minor (clubs or diamonds). Opener's preference call (2NT for diamonds, 3C for clubs) allows Responder with weak minors to select the minor of choice as if that were his one minor.
With extras, Responder hears the response and then bids 3S to agree the minor Opener showed, forcing (Opener might have started with both minors), bids 3NT if Opener "picked wrong," or perhaps even bids the other minor at the four-level (also forcing). Returning to Opener's major is to play, suggesting that the 2S call was actually tactical, wanting to spot a feature perhaps (this might instead show the other minor and forcing, if that makes more sense, or flags method).
That handles one or both minors and weak or strong, at the sole cost of not being able to show spades cheaply. To show spades, Responder could bid 3C with one hand, 3D with another (perhaps one is 5-card, the other 6+) or perhaps 3C is simply "asking," with Opener agreeing spades with 3, rebidding his major with a sixth card (for the 5-carders), or waiting 3D with neither.
After a 2S opening, the methods described in the Rexford-Eichenbaum system notes works.
After a 2D opening, we do not need a means to show both minors. However, criss-cross has some merits. 2H would then show spades (a simple transfer), which allows spades to be shown as weak or as GF. 2S would show hearts, which eliminates the ability to get out at 2H, but if you play RONF otherwise, this is no real loss.
Perhaps something like this is best.