A new approach (2)

2/1 GF except rebid is imo the way to go. Playing jumps as invitational loses too many options, and bidding 1NT with an invitational good 6 card suit can sometimes make it difficult to show your true strength later on. It also makes a semi forcing 1NT response possible, which can be a winner over forcing 1NT.

However there's always that 1 difficult auction: 1♠-2♥. With my new partner we respond as follows:
2♠ = any minimum without 4♥
2NT = 16+HCP, no singleton or void, not 4♥ (so 5332/54m22/6322/7222)
3m = 16+HCP, 4+m (not 5422, not 3♥)
3♥ = 16+HCP, 4♥ / 3♥ + singleton/void
3♠ = 16+HCP, 6+♠, 0-1♥, no side suit
3NT = not used!
4m = minimum, 4♥, 0-1m
4♥ = minimum, 4♥, 5422

3NT isn't used, but a useful agreement could be 5=4=2=2 with values in the short suits.

The 2NT rebid is a little homegrown tool, useful to find 6-2 or 5-3 ♥ fits while you know opener doens't have immediate ruffing value. This also makes our 3♥ rebid better defined: it always shows potential either by ruffing value or because of an extra trump.

After 1♠-2♥-2♠ (this is forcing for 1 round btw - opener can have up to 15HCP and can still have a 3 card ♥ fit), responder can just rebid 3♥ to show the invitational variant. With a GF responder can bid natural (except 3♥), or use 2NT as a relay to ask about opener's shape.
After any other rebid from opener the situation is GF.

There is 1 hand which may be difficult: opener is minimum, and responder has a GF with 6♥ and no ♠ fit. In this case, you can't find a 6-2 ♥ fit.

These days some pairs reverse the meaning of 2♦ and 2♥ responses over a 1♠ opening, to avoid similar problems. Although it has merit, it also brings many problems.
- For starters, there's no well defined structure after 1♠-2♥ showing ♦ (as an example, in IMP magazine there was an article on the switch: a few pages on continuations and theory after 2♦, and just one column on 2♥). Opener lost a lot of valuable space! Should he still be looking for a ♥ fit? Should he support ♦ with minimum hands? Etc. In my previous post I mentioned that we have described our 1♠-2♦ very well (usually 6+ cards), so we could get away with the switch.
- On the other hand, 1♠-2♦ (showing ♥) isn't perfect either. Do you want to be able to stop in 2♥ or not? If so, you'll need to find a way to show your 14-15HCP hands with 3 card support. But this will make things harder to support when you have 18-19 with a 4 card support! So while you're creating more space, you should actually give up on being able to play 2♥ and use this to show minimum hands with 2-3♥.

My conclusion on the switch is mainly that it doesn't fit well in a "2/1 GF except rebid"-structure. If 2/1 is an absolute GF, then it may make sense. I've also seen people include weak hands with 6+♥ instead of invitational ones. This is probably playable, since 2♥ rebid from opener isn't forcing anymore, but probably brings up some problems elsewhere in the system.
Either way, since you have to give up a lot (response structure + 1♠-2♥ continuations), it's imo not worth the trouble.