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For a cheap upgrade and additions:
In my C8, my most used eyepiece (for faint stuff) was a 20mm Erfle. Recently, after 20 years I got something a bit sharper - a 19mm Flat field eyepiece of the type sold by Smart Astronomy, Orbinar and numerous others. I also have a Meade 18mm UWA, which is fine, but the eyepiece is big.
For looking at planets -
a 10mm eyepiece (200X useable most nights)
an 8mm eyepiece (254X for when the seeing is better)
a 6.4mm eyepiece (320X for the lesser number of nights, when that power is useful)
a 5mm eyepiece (400X for those few nights a year, when I can get a decent image at that power)
If you have a 2" diagonal, surprisingly, even a cheap 30mm Ultra Wide Angle eyepiece gives pretty impressive views (providing you don't mind distortion at the edges). Bintel and Andrews used to sell one for $80, which had a Barlow screwed into it to give 20mm (but with the Barlow attached, it was only a Superwide angle eyepiece). But a more expensive one will be better, obviously.
Alternatively, a 2" 40mm Superwide angle eyepiece, will be heaps better than a 1.25" 40mm eyepiece (I tend to use mine with a broadband LPR filter to get rid of skyglow)
The f/6.3 reducer I didn't use much visually because at the effective 20mm eyepiece focal length (20mm without reducer, 12mm with reducer) I didn't see galaxies as well. But that doesn't matter so much for brighter objects.
So what I am suggesting is
0.5 to 1mm exit pupils for high power,
2mm exit pupils for galaxies and other faint DSOs,
4mm exit pupils for wide bright field,
3mm exit pupil with an Ultra Wide eyepiece because I like it.
With your focal reducer and a 40mm eyepiece, you can get a big 6.3mm exit pupil. But I've only ever found that useful once - when trying to see the Horsehead Nebula with a H-Beta filter.
Good luck with whatever you choose.
Regards,
Renato
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