I don't even look at barriers although they seem to make up a fair amount of the pre-race comment on the big Cups races (perhaps because it's the only time you get 20+ runners). Several points:-
1. Inside barriers are supposedly the preferred address, but;
2. Inside barriers can be a handicap for slow beginners.
3. Fast beginners wouldn't care if they're near the rail or out in the suburbs - they'll still lead the field into the first turn.
4. Wide barriers only matter if the distance to the first turn is short - probably 150m or less - check your track maps - I personally couldn't be bothered.
There's too many other factors to worry about - like which side of the bed did the jockey get out of.