4 pieces or 3 pieces need only be sorted out on gamish hands. 4-3S is fine in 2S - just pile up 6,7,8,9 tricks. But often need to keep trump control for 9,10+ tricks, so avoid S4-3 (allow only 3cS takes needed ruff). Use 2/1 F1 bids with 4SF for 3cS invites+; raises, jump raises with 4cS. Essentially 4SF asks 'partner do you want to try S4-3 game?' Raises tell him the 2/1 'stuff' is right and spades is right.