I think this is an interesting topic as has been said and the reasons for a preference one way or another as individual as all of us.
I don't agree with Herring about the similarity to SP. I think there are probably more similarities with SP than other forms of conventional fishing but for me personally, nothing will ever replace the fly. The fly is the key to me... fooling the fish with a fly especially one constructed by yourself.
I've had a go with the Sp's, albeit brief, when fishing in Tauranga with Uncle and it is certainly a fun and deadly method, but I didn't get the thrill
I get from a fly caught fish.
I think the world of fresh and salt are as poles apart as they could possibly be and while casting to Kahawai work up is a world of fun i couldn't use it as the definitive saltwater fly situation. In fact I don't think I could call any part of SWF in isolation the definitive part of SWF and there in also lies a major part of the appeal.
I have done most every form of trout fishing you can think of. I have done in excess of 1500 guided days on trout streams and heaven knows how many (Probably not as many as that) fishing for myself. I achieved most every goal I can think I ever had for trout and it represents, to me, a repeat performance now. Just about every day will be a repeat of something I have experienced before. You will always be learning, such is the nature of fishing, but the world of SWF opened up huge new horizons, things to learn and discover and that journey will never end because of the diversity of the ocean and it's surrounds.
I do agree with herring that being a good Trout fisherman doesn't make you at good SWF and that has been the appeal to me as there is so much more to learn. The transition for me from using an average of a 5 weight rod to casting the big guns of 9 - 14 was really an eye opener and it took a lot of practice to come to grips with that.
I have had experiences in the salt that would rival trout fishing for the stalking aspects... trying to will a JD to take a fly (Still trying....

) Is one such thing where not only do you "stalk" the JD but you get to see the JD "stalk" the fly... I find most snapper situations very akin to lake fly fishing with streamers and King fishing in a world of it's own.
Kahawai fishing is almost identical to smelt fishing... so there are parallels.
I think 80% of the fish I catch would be visual, so its not all blind casting by any means...
However, the majority of trouties I speak to have an interest in SWF and I believe more will try it with the information out there. Most salties see it as a curious eccentricity but do get interested when they see it in action and that you catch fish. I think that's one of the keys, people have to see it work.
The Wildfish series in Aussie did that... they saw the success of it and so were confident it would work. A bit more media coverage of successful snapper and Kingfish captures on fly here and it might be surprising how many people from different "styles and genres" of fishing join in the silliness..
Clark