stayman then transfer

I get this new (for me) convention from one of the Martens books: transfers after 1NT opening and normal response to Stayman. The author calls it Stayman plus transfer, which is quite misleading, we already play Stayman+transfer as responses to 1NT opening.

It works like this:

• after 1NT - 2♣ - 2♦ :
• 2♥ = weak, with both majors (Garbage Stayman)
  
• 2♠ = transfer to clubs. may be a weak hand with 6clubs-4M (reponder will pass) or a strong GF hand with 5 clubs and a major in 4 (if is strong, the reponder continues in a natural way, or in polish style by bidding a singleton)
• 2NT = natural, invitational
• 3♣ = transfer to diamonds, as above (weak or strong)
  
• 3♦ = transfer to hearts. Smolen style, 5 hearts + 4 spades
• 3♥ = transfer to spades, Smolen (5 spades, 4 hearts)
• 3♠ = ?
• after 1NT - 2♣ - 2♥ :
• 2♠ = transfer to clubs (long clubs plus four spades)
  
• 2NT = natural, invitational
• 3♣ = transfer to diamonds (long diamonds plus four spades)
• 3♦ = transfer to hearts, slam invitational
• 3♥ = natural game invite
• 3♠ = heart fit, splinter
  
• after 1NT - 2♣ - 2♠ :
  • 2NT = ! transfer to clubs (long clubs + four hearts)
    
  • 3♣ = transfer to diamonds (long diamonds + four hearts)
  • 3♦ = ?
  • 3♥ = transfer to spades, slam invitational
  • 3♠ = natural game invite

Which are the advantages?

• very easy to remember. especially for Smolen hands (you'll know for sure which is the major in 5 and don't have to think about it) and for hands when reponder wants to issue a slam invitation in major
• ability to describe weak 6m+4M hands. very usefull for pairs, you search first for a major fit
• not much to loose (see below).

What you loose?
After 1NT - 2♣ - 2♠, 2NT is transfer to clubs (in all other sequences, 2NT is natural invitational, but here is not enough space). This means that you'll have to find a way to describe an invitational hand with 4 hearts. Martens overloads the heart transfer: 1NT - 2♦ = heart transfer OR only four hearts in an invitational hand. After this:

1NT - 2♦
2♥ = make the transfer with 2-3 cards in hearts
2♠ = maximal hand with four hearts
2NT = minimal hand with four hearts

After 1NT - 2♦ - 2♥, the reponder bids:

• 2♠ = i have only 4 hearts and invitational. the bidding may stop in 2NT
• 2NT = i have 5 hearts, invitational
• 3any = natural, as after normal transfer, promises five hearts

Nice one, isn't it?