Smash DI on Shines and other stuff

[Johno]

Hey guys,
So I've noticed that a lot of top level players are starting to smash di a lot more moves and combos than before. Most notably, I've noticed how people have been smash di-ing shines and thunders combos. I'm not exactly sure which direction there are smash di-ing either. I believe that they sdi the jab on the thunder's combo up and they sdi the shine up and out. If I could have some clarification both on the how to sdi these combos/moves and on the application of sdiing them. Also, what are some other notable moves/combos that are useful to sdi and how do I sdi them. Any other info on sdi is appreciated.

Secondly, when is it safe to go for a shield grab during shield pressure? A lot of the time when I play falco, and I hit a marth's shield early with an aerial, they shield grab me. Is it always safe to go for this shield grab or are their times when I should just buffer a roll or pick some other option.

Thanks for all of your responses.

 

[OnStrings]

SDI-ing a jab upwards sometimes prevents you from being jab reset because it pops up you up. That breaks you out of Thunder's combo because you're not doing a slow getup off the ground.
SDI-ing falco's shines outwards (I don't know about up and out) makes it harder for him to get easy combos (shine dair shine dair shine dair). He's got to start chasing your DI.
Honestly i'm a huge noob with SDI, I just barely have regular DI down.

Shield grabs are generally good for misspaced aerials of non-spacies. If they hit your shield and they're close enough to grab, it's not a bad option, though you might get jabbed during the grab animation so be wary. Against spacies, you just get hit by the shine. Usually it's not safe, I would either roll or wavedash out of shield.