Use a low power eyepiece (FL >= 20mm) from a reasonably dark site - well away from light pollution source, min. 50km from major city, 20km from large town (parks "around the area" won't do if you live in a city; light pollution travels a long way) and you will see heaps of structure in M42 with the 6" Dob. Looks a lot better than the simulated picture you've linked above.
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