Bende, on 2016-May-03, 09:01, said:
Opener can then only stop below game after asking about the side suit, not about the splinter. This feels like a bit too many bids with invitational hands to me. They would also overlap as I suppose you can have four card support with both a side suit and a splinter, even if those hands would probably be unlikely to accept stopping below game.
My feeling is that showing a shortage is more useful than showing a side suit. Yes, you are likely to have both, but if you want to bid this with weaker hands that may stop in 3M, then your side suit will not be strong nor solid enough for opener to rely on for running tricks. So why bother with the side suit? Knowledge of the shortage is more useful.
You could swap those meanings. If you did, then your side suit showing 3M-1 would have stronger hands, as it is GF, presumably with some agreed solidity in the suit. But now there is no point in using 3M-1 for a GF bid that gives wasted space : 3M+1 is sufficient. This means that you now have 3M-1 spare.
You may care to use this as the strong splinter in that suit. This allows you utilise the next step up as a relay to find out whether singleton or void, useful for interpreting later ace asking, which you cannot do after 1M 4M-1.