I was wondering if you start seeing a shadow of the secondary at low magnification (large exit pupil) when using low power, for example the 30mm Nagler. I notice this sometimes when observing the moon with my f4.5 telescope, but of course, my eye's pupil is greatly reduced under those circumstances. I would imagine at some point, with increasing exit pupil, it could become an issue even looking at DSOs, but I'm not sure from a practical point fo view at what point this would happen, if ever.
My most used eyepiece is the Ethos 21mm - good EP, wide field and decent magnification for medium objects.
I do use the Nagler 31 - some objects are just viewed best with it. I do not see the secondary shadow when using it.
When a friend brought his Explore Scientific 40mm/62 degrees the secondary shadow was apparent and it was hard to observe with it.