Canon specify that using a high speed UHS-1 SD card the SL1 has a buffer size of around 1140 full size JPEGs or around 8 RAW images. So going for the fastest card gives a significant gain in the number of JPEG images you can shoot before filling the buffer (27 to 1140), but only a small increase in the buffer capacity for RAW images (6/7 to 8).
With the EOS SL1 / 100D set to Large Fine JPEG, I fired-off 36 shots in 8.7 seconds, corresponding to a speed of 4.1fps; the buffer took four seconds to completely clear. Switching to RAW, I managed seven shots in 1.49 seconds, corresponding to a speed of 4.7fps; this time the buffer took six seconds to completely clear. Finally setting the camera to RAW plus Large Fine JPEG saw the camera capture four shots in 0.98 seconds, corresponding to a rate of 4.1fps, while the buffer took five seconds to completely clear.