Every time I catch myself making comparisons of things that I do, or things that I have/haven't achieved to what others have done or are doing, I try to stop and think the whole thing through. Sometimes this can be beneficial, and sometimes it can be self defeating or self destructive. I think that it's something that comes up a lot in the dog world. Regardless of whether you compete or not at all, I think we're constantly comparing how our dogs are, what they do, how they do it, or what we've done with them to the same things that other people have done with their dogs. From things as simple as envying people who's dogs don't go into a barking fit when someone knocks at the door, to wondering why you haven't achieved some coveted title when someone else you know has achieved it in less time and experienced fewer difficulties. We're always comparing and contrasting.
I think that this can be potentially helpful if you have a positive role model or something positive to strive to achieve. If there is someone who is doing great things with their dog(s) within your breed and you would like to go down a similar path, they could definitely give you something positive to strive for. If you go about it with the right attitude and keep your focus on achieving your goals and how to get to that point, I think that comparisons can be helpful.
It's when we start to compare ourselves to someone else and it starts to become self defeating, that things can take a turn for the worse. For instance, there's someone possibly within your sport or your breed who is achieving things that you would also like to achieve. They managed to get to the level they're at within a few short months, while it's taking you those same months just to get out of the novice level. Things could get very frustrating if you start to beat yourself up for not being able to achieve the same thing in the same amount of time. Worse yet, you could start to take your frustrations/disappointments out on your dog, whether in training or in competition. It can start slowly, but it's an ugly path.
The thing of it is, every person is an individual and every dog is an individual. Just because someone who got their dog at the same time that you did, got the same breed, and from the same litter, that doesn't mean that both dogs will be able to necessarily achieve the same feats, or in the same time frame. Every person has different constraints on their time. Every person has different things going on in their lives that will influence the outcome. And every dog has their own personal quirks, likes, and dislikes that will present various training or just every day living challenges. Not every person is going to experience the same problem. Not every dog/handler team will experience the same triumphs.
In my own rambling way I guess that I'm just trying to say to compare yourself to others only when it will lead to positive things. Only you know what is truly going on with yourself and your dog and only you can make the judgement calls that are best for you both. Surround yourself with those who will genuinely be happy for you, encourage you, help to build you up, and be a support system to you when you are having your down times. Leave the negative comparisons and the negative people by the way side because they will only serve to tear you down. You and your dog are individuals and that, in and of itself should be something to be proud of!