It depends how well your current TV displays SNES over direct RGB SCART. If your TV supports higher than lineX2 then it will look sharper with the OSSC.
There are different revisions of the non 1-CHIP SNES with different video quality. The early consoles have more blur than later consoles.
Here are some captures in lineX4 so you can compare:
Is SNES the only console you want to use with the OSSC?