I hate to say it, but watching the 1st and 2nd seasons again, I'm starting to think Berman had the right idea by changing the music the way he did. As exciting as some of the early themes were, they DO make the show seem awfully corny and dated now.
The quieter, more classical music of the later seasons somehow made the show feel a LOT more sophisticated.
It may be repetative, but Ron Jones' work in episodes like The Defector and Booby Trap I completely adore. It does exactly what a TV soundtrack should do - add tension.