I've never understood the appeal of this sort of thing. The idea is create a common interface to a bunch of different databases. But you still have to write or generate SQL that is specific to whatever database you're actually using. Outside of a very narrow range of apps (eg SQL-IDE kinds of tools), you're going to be both coupled to a specific database and limited by lowest-common-denominator design constraints in the interface library. Ugh.
Having to fine tune SQL, or change store procedure syntax call, is a tiny change, compared to rewriting from scratch the complete database binding code.
Plus for many kind of applications, the ANSI SQL coverage across RDMS is quite ok.
We have the same product that runs against 4 different DB's with 99% SQL being identical. Sure you sometimes need to hunt on whether a standard SQL feature is supported, but they mostly are. And even if the query dialect for the feature is a bit different, the DB access code remains the same.
