[P0STM0RTEM]

Too bad 5+ wasn't included as an option. That would receive my vote. Any flatter and would conceal ♠ length with 1N or 2N relying on a later check back for a major suit fit (just as I would over a 1♦ reply).
♠: Must have either <5♠ or longer ♣ to open 1♣. Therefor 4 Max.
♥: Raise ♥ with 4+, wouldn't bid ♣ with only 3 and longer ♦. Therefore 3 Max.
Thus 4-3-1-5 or shapelier would rebid 1♠, a minimum of 5♣.

[KurtGodel]

I think this one largely depends on where you learned to play bridge, in England (where I'm from) it's almost taboo to bid this way holding fewer than 5 clubs. Maybe it's just the way I've been brought up, but to me bidding two suits shows an unbalanced hand! I've tried playing the American/French/Polish...etc way, but I really dislike it, I doubt that one is much better than the other if you have a full range of other agreements. I now normally play transfers over 1♣, so we don't miss our spade fits when responder is weak 4-4 in the majors and opener is balanced with 4 spades.

[jogs]

Found a board where both directions made 1NT.

{comments}

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[Vampyr]

 KurtGodel, on 2015-September-15, 03:40, said:

I think this one largely depends on where you learned to play bridge, in England (where I'm from) it's almost taboo to bid this way holding fewer than 5 clubs.

The NT range you are using plays a part in this. The American etc style finds the 4-4 spade fits when opener has a weak NT. When playing weak NT, that ship has sailed already. When opener has a strong NT the partnership will on average have more combined values; so perhaps finding the spade fit is less important?