I love seeing sharks without the aid of feedings. However, when I do they are never as close or stay around as long.
It is my understanding that most shark species are opportunistic feeders and do a lot of scavenging as apposed to hunting. Even great whites dont insist on making a kill to feed and will gladly tear into a dead whale floating on the surface.
So in many ways shark feeds fall into the category of "natural behavior" for the sharks.
I have not seen/read any evidence at all that shark feeds create sharks that are more prone to attacking humans than sharks that have not been fed.
I have seen/read about sharks hanging out near areas close to busy beaches where fishing boats clean their catch and toss the refuse into the water. This seems to be a much more hazardous situation since it brings the sharks into areas where swimmers, snorkelers, and surfers can be mistaken for natural prey as they are on the surface presenting a silhouette that more resembles a sharks natural prey.
I have not done every shark dive out there of course, but the ones that I have done were not real close to swimming/surfing areas.
The few stories I have heard of divers actually being bitten by a shark during a shark feed have nearly all included some major breach in protocol by the diver in question. In every case I am aware of, the diver bitten was one taking part in the feeding and not one of the observers. The bitten diver being so used to feeding the sharks that he/she becomes complacent and does something that is ill advised at best.
In my thinking, the positives of shark feeds (basically education for the divers and good publicity for sharks) far out way the negatives.
Given all of the preceeding info