Suraj, You will get some of your best yields in greater Brisbane in this area, whether or not this is the correct thing to be doing is an important question as you point out. Pluses and minuses as with almost all investments.
I suggest to people that they spend 30 minutes in Logan Central shopping centre, sit down have a coffee and just observe the people to get a good idea for the makeup of the area, if this isn't possible then there's plenty of opinion on somersoft to search for.
In terms of long distance research if you aren't able to put feet on the ground yourself I suggest phoning a few local property managers (avoiding the selling agents and looking for the specialist PM's) and have a chat about the different suburbs and areas, tell them you are thinking of buying an IP and would be looking for a manager would make them more keen to have a chat.