I've used other language/database combinations at various times. For business applications in particular, I find the Progress environment to be accessible, rapidly prototyping, which makes capturing business requirements simpler.

I've used many other DBs including Oracle, DB2, Informix, Ingres, Sybase, Postgress, MS SQL. The Progress OpenEdge is simple to administrate (do not need an FTE), and very stable. Once you switch it on, it simply runs and runs.