Should I keep what I think is a RIR Roo?

You're going to get mixed reviews on this. I too bought 4 RIR pullets. All along 1 in particular was dominant, sassy, and brave. I loved milady. Anyhow, like you about three weeks ago a red comb and waddles emerged. By the time I realized she was a he it was too late. I just love him. He is very protective of the hens and I wouldn't dream of separating them. They are 7 weeks old. I have heard that RIR roos can be mean, and time will tell, But I love my boy.  If you really don't want chicks you can always make sure to collect the eggs.
 

If you post some pictures of your chicken in question, we may be able to help you figure it out for sure.

If you don't want to raise any chicks, then it's entirely up to your preference.  Personally, I'd keep him because after adding a roo to our flock, I wonder how we ever did without (and we have no plans for chick raising any time soon, either...unless some interested friends/family go over the edge and decide they want to start flocks of their own ).

Just make sure the area you're in permits roos and that you (and any neighbors with the potential for impact) understand that roos crow, you can't stop them, and any time of day/night is game (though they usually won't crow at night without some source of light or unless something is disturbing them).  Roos also don't often do well with human beings that are less than 4ft tall, so if you have children, you may want to think twice.

However, assuming he gets through puberty (and they can be crazy, hormone driven nutbags during that time) and turns out to be a pleasant individual, they're a joy to have.  Very talkative, inquisitive, and typically vigilante; they make a very interesting contrast to the behaviors of the hens.
 

I pretty much free range and to me a good rooster or 2 is invaluable.  If you get a good one he'll do a pretty good job of keeping watch and protecting his flock.  My first rooster taught the cats to leave chickens alone in 1 day and the second day he taught my dog.  He would chase the hens to cover from an owl or hawk. 

If you have a small yard or confined birds a rooster would only be of use to you if you want chicks or just like the way he looks.

Quote:

Originally Posted by klmilia 

  And why should I keep him if I only wanted pullets for eggs.  Not planning to hatch any chicks.

No reason to keep him unless you want chicks. 

I think its personal choice and if noise is a conscern . I enjoy my Roosters .. But I do Hatch .. But If you never plan on needing fetalized eggs .. they dont serve a purpose .. I Just like them .. Watching them strut and show off etc.

I checked out your pictures, he looks exactly like my supposed pullet. I say absolutely. Also they say the legs can be thicker, my guys legs are almost twice the thickness.
 

Look's exactly like my RIR roo did at that age.  He was a real standout from the girls with his much more developed comb and wattles.  The pullets didn't get that kind of comb/wattles and especially not with that much red, until just before they started to lay.