Here's my take:
the KA isn't necessarily weak (stock yes, but it's fine after some mods or turbo)...it's just that for the HP/money....the SR is normally the best way to go, depending on your situation.
Usually, if people buy a s13(not sure on s14), the engine has over 100k on it..at least. so adding a turbo on it would probably require a rebuild of some sort, and it'll all come out to more money then a basic sr20 swap...(there are always exceptions), and that's what makes the swap so tempting. most of the sr20's have only 30-50k on them, so for less then half the price of a new KA24DE, you're getting a nicer engine that's just been broken in...although, some of them were beaten on quite a bit...so there's always exceptions there.
if you have a newer engine though, then a turbo kit for the KA might be better for the money....
of course, it also depends on where you are, are you going to have to worry about emissions, inspections, etc. some states won't let you have an SR at all, some don't care as long as you pass the sniffer test, there's a lot of variables.
And also, what kind of an engine do you like, revvy ones, with a little less torque, but better usage of it at the higher RPM's? or something with more torque but not as good usage of it at the higher RPM's? It's pretty much a trade off.
pretty much the whole debate is almost purely decided on an individual basis. for some, the SR20 is the best solution for moderate HP. for some, the KA is the better solution for moderate HP.
as far as SCC, they did get a special price, so yeah, you might be spending an extra 500 then them...depends on where you get the engine, who's doing the labor, and how much HP you want.
for me, turboing the KA is a better choice, since I already paid the price for a new engine before I even heard of the SR20. Now, I still want to turbo my KA, only 15k miles, I know exactly what's been done, and I'll know exactly what I might need to redo when I turbo, but I'd also love to have the SR. seems like every 240 guy/gal wants 2 240's, one with a KA DET and one with an SR20. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/hehe.gif" border="0" valign="absmiddle" alt=':hehe:'>
what I'd suggest is this:
1-Figure out what HP you'll be happy with, 200, 250, 300, more?
2-Find what requirements your state has on engine swaps and stuff, would it be outright illegal, or just as long as it passes sniffer tests? and if it is illegal, are you okay with that? For instance, I live in Oregon, some parts require testing, some don't...so if I lived in the country somewhere that didn't have any emissions testing, I'd be much more prone to get the swap.
3-Find out how much an SR20 would cost you to get, I'm talking about locally...for a shipped engine, I've never seen anything lower then 1500...even incomplete.
4-Then figure out how feasible the swap is for you personally. would you have to pay someone else to do it, or could you do it yourself and some friends.
*If someone thinks any of the above items are wrong or biased, please say so...cause I really tried not to bias it one way or another.