Hi David,
Easy! Use the very same eyepieces you are using with your refractor with your C8!
A C8 has no different requirements from a refractor. If the new scope was a Newt, then there's a few things to consider, but not with an SCT.
And yes, 1.25" EPs use all the light collected, just like it does with your refractor. No different. Bigger aperture does not mean needing to use 2" eyepieces. Otherwise I'd need to use 3" eyepieces with my 17.5" dob...
The difference between using 2" or 1.25" eyepieces has nothing to do with aperture. The reasons have to do with other considerations, but not having a larger aperture. You can also use 2" eyepieces with a 2" scope...
Good to know the why so you can make the best choices for you.
Take two straws, same length, but one larger in diameter than the other. When you look through each, what do you see? The larger diameter shows more of the background than the narrower straw. This is more significant when it comes to long focal length eyepieces. You will find that there is a distinct maximum length of focal length in both barrel size and Apparent Field of View (AFOV).
In 1.25" EPs, with and AFOV of 52° the longest focal length you will find is 35mm. Yes, you get a 40mm 1.25" eyepiece, but the AFOV will be smaller, and it will show exactly the same True Field of View (TFOV), that is the exact same amount of sky. The longest with a 68° AFOV is 24mm, with 82° it is approx 15mm, and 100° it is 13mm. You just cannot get a 1.25" EP of 30mm focal length with an AFOV of 100° - the barrel size just won't allow it.
With 2" eyepieces, the focal lengths of course get longer for the corresonding AFOV. 52° approx 50mm, 68° it is 42mm, 82° it is 31mm, and 100° is 21mm. And again, you just cannot get an EP of 50mm with a 100° AFOV as the barrel just won't allow it.
Alex.