A good 8* SCT will need good circumstances, both of the skies above and the instrument itself, collimation, thermal equilibrium, to perform well at higher magnifications and the planets. If all of that is taken care of, the C8 is great.
If not all is taken care of, and is difficult to address, than the forgiving nature of a good apo and especially a good doublet come into play. It will perform to the best of it’s ability on any night after a half hour or so, many times even a bit sooner.
As an example, I have had absolutely stunning nights on the 3 big planets with my 7” Questar 7, some nights. And I have had it outperform my 4” fluorite doublet on quite a few nights. On most nights, the 4” fluorite showed quite similar detail, unless the seeing momentarily improved.
Where the Q7 always performed was in the ease of it’s views, always in the range of it’s 24-12mm Brandon eyepieces, never needing anything beyond that. And it always just cruised at 180-230x, where the refractor would already be strained. Having more of the 140-160x sweet range.
In return, the 4” fluorite always performed and only shoed the limits of the seeing. The bigger instrument showd that too, but many a night compounded by showing it’s own limitations of thermalvequilibrium or the lack thereof. Collimation was fixed at the factory and perfect.
But the real take from it all for me was, that both the 4” and 7” are limited by their apertures to really bring in the finer planetary detail. My custom Matthias Wirth 16” f/5 with outstanding optics made that clear the very first night I used it on Jupiter. After decades, it was an astounding jump in observable detail. But it comes at the price of a much bigger instrument that is sensitive to thermal conditions and the quality of the seeing. At times taking 2 hours to cool and reaching (near) optimum performance. But when it does that, it is well worth the wait. As a consequence, I always start with a smaller refractor to judge the seeing when observing the planets and take out the 16” when seeing looks promising.