You will have no flickering on TV, but more input lag, because the TV deinterlaces the picture. It depends on what is more important for you.
There is one more Retrotink “buget” solution:
Wait for the Retrogamingcables Nintendo all-in one Component Cable. It will work on Gamecube, SNES and modded N64. So you can swap the cable between SNES and GC and actually have an increase in image quality (upscaled S-Video will look worse than RGB directly connected to the TV). 105€ for Retrotink, 41€ for the cable, 10€ for N64 S-Video (you need a modified PAL one!!!), 10€ for PS2 component. Just estimated, without shipping. You can expand this with the OSSC whenever you want
The main problem of the Retrotink 2x are the avability and prices of the component cables. The more consoles you get, the less it’s a budget solution.