To continue from below, we have:

So 1S-1NT--?
2C: With a four card or longer minor, if less than 17 exactly 4 in minor and 5S and if less than 13/14 will have 2 or 3 Hs (this rebid will also include 5-3-3-2s if you open 1S with them and don't pass 1NT)

After 1S-1NT--2C-?

2D: Positive, Game Force opposite 17+ OR both minors signoff
2H: 5+Hs, up to 9
2S: 2+Ss, up to poor 8, or singleton S and no good bid up to poor 8
2NT: 6+Cs, 8+
3C/D: Long minor, up to poor 8

The change here is that 2D can be a both minors signoff and 2NT shows long Cs 8+. The both minors signoff is moved from 2NT to 2D (and the long Cs 8+ moved from 2D to 2NT) so that there is a both minor signoff available at responder's next bid.

After 1S-1NT--2C-2D--?

2H: 10-13, 5Ss, 2-3Hs - now 3C by responder is to play in opener's minor
2S: 13/14-16, 5S, 4 in a minor. 3D is a forcing asking, 3C is to play in opener's minor
2NT: 17+, 4+Ds. Now 3D by responder is attempted signoff, 3C re-asks
3C: 17+, 4+Cs, NF if responder is weak with both minors. 3D re-asks
3D+: 17+, 4+Cs, too strong for 3C

This structure (and the corresponding 1H structure) is ready for alpha testing - here we now wait a bunch of months and see how it would perform on any hand that we see on vugraph or that we play. Questions include:
a) Will giving up 2D to play cost?
b) 1=4=5=3/1=4=3=5 have no good landing spot - how should they rebid?
c) Will 1S-1NT--2C-2D--2S gain over standard?