Here's some quick pics I took of Super GnG. The first is the actual cart running off a SNES via RGB to my 14 inch PVM:
The next is from an old Thinkpad I got from Goodwill that I'm running SNES9x on. I installed Soft15Khz on and output to the same monitor via RGB:
They are really close. The pics make the dimensions look off because I took them from slightly different distances but the modeline I used does seem to output just as a SNES would. The SNES has slightly blurred edges that some might prefer while the laptop seems to output a stronger signal with harder edges. The images were taken with my phone so they aren't the greatest but I've always wanted to compare the two.