I've replaced the rubber under the buttons. In the end I also added the original snes buttons and the rubber under the d-pad. The test is the same as the last week: Super Mario World on Higan balanced with sfc30 (bluetooth and latest firmware) vs wired DS4 vs Original NTSC snes.
- The results are better, but not perfect. Despite now being able to time the jumps, it still feels off and notice a delay. It improved after enabling game mode on the tv, but still.
- Dual Shock 4 wired is the one that gives the closest feel to playing it on snes.
- Not even Higan comes close to the feel on the original hardware.
- I did the opposite experiment, using the rubber and buttons on a real snes gamepad. It feels a bit harder than a real gamepad, but I still could obtain results comparable to my main snes gamepad. So this would mean that it's not only the rubber and buttons causing problems on the sfc30. There's something else that adds to the delay and time to press the button.
For the record, I did not like what I found opening the SFC30. The L R buttons use a bending system instead of the metallic piece to move around found in an original snes gamepad. The buttons on the sfc30 return due to plastic going back to its originall shape, while in the snes being the rubber the one that pushes it back.
My final opinion is that if you are planning on playing seriously, don't waste money on this. The DS4 is the best modern gamepad for playing d-pad intensive games right now.