>
> My initial suggestion was to use a shortcut syntax using the standard
> MERGE keyword, so we would have two MERGEs - with a standard syntax

and

> with a shortcut one. I don't see what problems it would provide us

with,

> but AFAIS many of you don't like this option.
>

Why ? It is good idea.

First MERGE statement can be as SQL2003 says :
MERGE INTO <target table>
USING <table reference>
ON <search condition>
WHEN MATCHED THEN UPDATE SET <set clause list>
WHEN NOT MATCHED THEN INSERT [ <left paren> <insert column list>
<right paren> ]
[ <override clause> ]
VALUES <merge insert value list>

And the second shortcut can be something like :
MERGE INTO <target table> [(<field_list>)] VALUES (<value_list>) ...

-Laco.