Hmmm, ...the 6 inch f/4 reflector has a few advantages over the 6" f/5 refractor. The refractor is an achromat so it's only really usable for NV when filtered at 685nm or Ha. You can use it for visual but CA will show for bright stars/planets or at higher power.
I think the imaging newt doesn't suffer from CA and you can use it for visual with an extension tube.
Just comparing the two, the images are sharper with the refractor. They are close though. Yes, some brighter stars get blown out a bit. I only use it heavily filtered. I can do more comparisons, but so far the refractor has won. I am not sold on the 6 inch F5 refractor for visual yet, however, adding the aperture mask works very well on the Moon and Planets. Though smaller aperture. I have not had the chance to use it in a dark sky. Obviously a 5 inch F7 apo would be much better. And maybe even my 103mm Vixen would be better. But it seems to do well for night vision.
The imaging newt has a huge central obstruction and I've found it isn't great for visual. Don't get me wrong, it's a great scope for imaging purposes and NV. Adding a coma corrector makes for a gigantic stack. I know they sell a really expensive one made for these, but doesn't seem worth it.
The only benefit I see with the 6 inch F4 is using a filter wheel is possible. Though I don't personally like using the filter wheel much.
If I wanted a visual newt, a 6 inch F5 with a normal secondary mirror would be much better.
So I think I will sell the 6 inch F4, the filter wheel, and the MPCC. I could use a bit of money anyways as I recently ordered a Tak 76 DCU which I will be using F12.5. I've been doing half visual half night vision recently. I like seeing the color of the stars, the Moon and the planets.
My new Vixen AP mount is really good with my Lunt 50mm double stack. And I figured the Tak 76 was a good match for the mount.