Lee, although I use the EP500, for general orchestral music the EP350 should be entirely satisfactory. The DSP processing in the EP500 prevents over driving the sub at extremely high listening levels but doesn't in itself extend the bass response. The pipe organ material you mention is something I also listen to and is the area(down to, say, 16Hz)where the EP500 has an advantage.
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Enjoy the music, not the equipment.