From my experience: d+4 is for crushing certain things and getting in a quick hit which you can cancel into Clone. d+1 is for stopping jumpers, but you have much better options (or A much better option, with 2,2, but I'm sure there are situations where perhaps d+1 would be preferable, due to frames and such). d+3 I don't really advise, simply because if you do d+3 and then try to dash for pressure, you often get Ice Ball.