The SWF (Salt-Water-Flush) definitely covers more ground than an enema, but we don't always need the small instestine and stomach flushed out. If there is balance there, sending a bunch of salted water through it will upset the balance. If your imbalance is centered mostly in the colon, it's best to just address the colon. Apply the bandaid exactly where it's needed, as it were. ;)
So ideally, one would start with an SWF (Salt-Water-Flush) to take toxins out of the entire tract, and then do a series of colonics/deep enemas as a more focused cleanse. :)