Adam, sorry guess I was not clear. What I said was that the MS Sql server + R strategy of baking in ML in PLSQL is appalling and doing something like what you are doing with DL4J is perhaps the right approach.
The multi GPU support rant was for SQL Server + R, not DL4J.
"You've also for some reason decided to attach an open ended coding library where you can do whatever you want to a database?" I didn't catch this part.