Yes, it is true, the Antiochian clergy are only to wear a cassock on church grounds, while they are to wear the black suit & collar when out in public. This is the edict of our Metropolitan, and as clergy, we must be obedient to him.
To be honest with you, I have had mostly positive reactions when I wear the collar in public. For example, I was visiting someone at local jail last week; I was wearing my collar. As I was waiting at the little window where you converse with the inmates, a prisoner in a wheelchair rolled by and saw me wearing my collar. He put his hands together in a "prayer" position and seemed to ask me to pray for him. I gave him a blessing through the window. I had a clerk at Best Buy ask me for a blessing as well; she probably thought I was Roman Catholic, but whatever, it didn't matter; if that blessing (God's - not mine) drew those people nearer to Christ, then the collar served its purpose. A priest in a cassock may have a similar positive reaction from people, but in what I have seen, at least in America, the cassock usually evokes stares that say, "What the heck is that?" The collar, on the other hand, is immediately identifiable with Christian clergy. It would be great if the general public could identify a cassock with Orthodox clergy - but we're just not there yet. Most people who see a cassock won't even identify it as Christian, even if a pectoral cross is worn. They seem to bypass the Cross and look at the dress most of the time.
I don't have a problem with any priest who wears a cassock in public, so long as he is being obedient to his hierarch. That's what it all comes down to - if the priest is obeying the dictates of his bishop regarding clerical wear - whether he is told to wear the collar, the cassock, or given a choice - then all is well. If he is disobedient, then it poses an issue. The matter is simply one between the priest and his bishop; while all others who observe his dress - whether laity or other clergy - are certainly entitled to their opinions, no one should judge a priest based on what he wears in public. Again, it is between him and his hierarch.