ThanksWith a RF you normally have to use an "autofocus" strategy: put the subject you want in focus in the centre of the viewfinder, focus, recompose, take picture.
With a SLR you can keep the subject you want in focus on the edge while focusing.
Some RF have an "all patch" viewfinder though, you can focus without recomposing, but the image in the viewfinder can be very confusing, you have to get used to it.
I find it slower, but I am an SLR guy mainly and I don't practice street photography. The slight loss in focusing speed is to be considered together with the quietness and small size of the camera. A RF with leaf shutter can be extremely silent. My Voigtländer Vito CLR has a Prontor 500 LK which is basically inaudible. Leica cameras have a focal plane shutter and are not as silent, but much quieter anyway than any SLR. RF cameras are generally speaking much smaller than SLR.
RF have a viewfinder which is relatively bright also in low ambient light conditions, there is no coupling between lens and body (which raises complexity, slows actuation, introduces noise and vibrations), and especially there is no mirror slap (big noise, big vibration problem).
With an SLR for maximum quality shutter times like 1/15, 1/8, 1/4, 1/2 should be used with the mirror locked up. That's something you can do when using a tripod.
If you find yourself using 1/15 free-hand with a SLR, and supposing you are holding the camera steady enough (very wide-angle lens, bean bag, whatever) you are leaving some quality on the table because of the mirror-induced vibration. It might be that a small quality decay is visible also at 1/30.
In a RF you normally see a central patch where the image has a double contour (either vertical contour or horizontal contour) if it is not in focus. Normally the rest of the image is not "patched" and you don't see anything special, I mean outside of the patch everything is always in focus. Somebody like this, somebody don't. If the lines of the subject are not what works with your RF you have to rotate your camera to be able to focus, e.g. to put it vertical, focus, then put it back horizontal (not that it happens often).
It's a bit like focusing relying only on the central stigmometre.
If you want to experiment, I suggest you buy a second-hand cheap RF such as a Canon Canonet. In the right environment they can be just the right tool for the job.