A good reason to use the f+3~spin combo is somewhat better oki as you're at more + frames by the time it ends and can easily put more pressure on - if you whif a divekick you basically immediately cross the dude up before he even has a chance to do a wakeup attack. So if you opt for that, your midscreen combo should be like this: 1,1,2~spin, NJP, jk~divekick, f+3~spin. I don't really get it why most people don't do the NJP, it's super easy - you just have to tap forward just when the first spin animation finishes to make Lao make a small step forward for NJP not to whiff. The only reason you would want to drop the extra damage (2% I believe) would be playing online as it's harder to connect f+3 when it lags. If you get a wall combo I guess that 2,4, 1+3, 2 stuff is generally better as you've got a good position on the dude even without the frame advantage