If you use a collar, make absolutely certain you do collar condition him. There is no reason in the world for that to be an ugly process. Have someone help you that REALLY knows what they are doing - a pro would be my recommendation. Easy to ruin a great dog with a collar, but a well trained collar dog is beauty to behold. I use one all the time - one setter, six Goldens, two Labradors (one FC, one MH, two SH, and some darn good hunting dogs).
On the other hand, collar or not, your obedience is faulty at distance, which means it needs a lot more work at close range. A pheasant farm is a great place to work on this. Repetition, repetition, repetition is the key to dog training. Come to the whistle no matter what is what you need, and when you have it completely reliable at 10 yards, change to 15, then to 20 and 30, etc.
Even the best dogs, once in a while, if you do not train all the time, will get a wild hair and not respond. That's when a collar really works, but you never ever teach with a collar. You teach teach teach, then once the command is 100%, you reinforce with a collar.
My 2 cents
