soil or soilless

getting ready to do my second grow and have done a lot of reading
just wanting to get peoples opinions on the pro's ans con's of either
i'm looking at either organic peat based soil with lime and neem in it
called gro or soiless mix called canadian express max yeild,link below
Switched on Gardener
also are 9 litre pots big enough for flowering?
cheers

anyones opinion is asked for thanks

Well, that should be fine. But it doesn't matter too much, in my opinion. You could get typical potting soil from your local hardware store and put in some decent powder fertilizer. I like to buy distilled water and use that. Sunshine mix is a good soil to use.