Thoughts on a convention?

My partner and I are thinking about adopting a new set of raises over one 1M openings. Among other stuff, we'd like to differentiate between a weak (say, 5-8) and a strong (9-11) simple raise. A friend of mine suggested a scheme, which I've slightly modified to look like this:

1-2: natural, GF or 5-8 hcp, 3(4)

• · 2: to play, unless partner is GF
• · 2: 16+ hcp, 4+
• · 2NT: 16+ hcp, 4+
• · 3: 16+ hcp, 4+
• · 3: 16+ hcp, 5-3-3-2
• · 3: 16-17(18) hcp, 6+
• · 3: (18)19-20 hcp, 6+

When I say 3(4), I mean "usually 3 hearts, but may be 3=4=3=3 or similar".

Rebids by responder:

• If responder doesn't pass 1-2-2, the meaning of his 2 bid becomes GF, natural, and the bidding continues naturally
• On other opener's rebids, 3 shows a minimum heart raise (5-6 points), 4 shows a maximum (7-8), other bids are as if responder had a GF hand with diamonds
• With a GF hand and heart support, we bid the 4th suit (e.g.  3 over 1-2-2)
• 3NT is always a suggestion to play
• There are no non-serious bids

What is your opinion on this treatment?