I got to hear an A/B comparison many years ago in a TacT system where they played it back to back uncorrected and full-range corrected using the same music. I forget the speakers they were using, but they were high-end, 3-way speakers. If the character of the speakers was changed, it was FAR outweighed by the effects of the room correction. So I'm not sure I buy the argument that correction above 500 Hz is detrimental on balance.
That said, bass is BY FAR the hardest issue to deal with in terms of room correction. My opinion is if you get that solved you can much more easily deal with the mids on up to get satisfactory results. I'd think correcting up to 500 Hz will go a very long way toward realizing your system's potential without a major room overhaul or multiple and intrusive bass traps. Just my $0.02.
That said, bass is BY FAR the hardest issue to deal with in terms of room correction. My opinion is if you get that solved you can much more easily deal with the mids on up to get satisfactory results. I'd think correcting up to 500 Hz will go a very long way toward realizing your system's potential without a major room overhaul or multiple and intrusive bass traps. Just my $0.02.