I upgraded from the Walsh 5 first to the Walsh 5 Series 3 and presently the Walsh 5000. The improvements over the original are substantial: a much more detailed and transparent mid range, tighter and more tuneful bass, and a seamless coherent sound providing for a wide and deep layered sound stage. Dynamics and power are effortless. Extended listening with no fatigue is guaranteed. I would recommend that you do an extended audition of the 4's, optimizing the room and setup. If you like what you hear, the upgrade will then be a slam dump winner. So I do recommend the upgrade. And the people at Ohm always stand behind their product and offer a 120 day try before your buy policy. You have nothing to lose.