Boxer-mom here! I currently have a 2 year Boxer named Rascal - he's in my avatar. He's the second one I ever had, and at this point, I can't imagine living without one.
Boxers are what I like to call exuberant dogs, especially when they're young. They're active and love to play. They also mature slower than other breeds, so it's common for a 2 or 3 yo Boxer to still be rather puppy-like their activity level, desire to play and in some behaviors.
Here are some pros:
IMO, they're a lot of fun to live with. They are generally people-dogs and love to be with their humans. We've socialized Rascal so that we can take him almost everywhere with with us. You've probably seen in some of your research that they are reputed to be good with kids and can be great family pets. Both of my Boxers are/were very affectionate. Both have been good alert dogs, but not excessive barkers in general. They are also very intelligent and really respond beautifully to the right kind of training, which IMO, is reward based (clicker, treats), not "crank & yank".
Some considerations:
Without proper training, exercise and socialization, Boxers can be hard to live with. That's why there are so many in rescue. They're a breed with so much potential, but can be terribly misunderstood in the hands of an ignorant/unprepared owner. They can become very destructive, and develop other behavior problems if they get bored or don't get enough attention. They are a quintessential pack animal and will not be happy if constantly separated from their pack/family. They do require daily exercise, which you're probably used to with 3 Labs. Actually, I think a Boxer puppy and your 3 YO Lab could tire each other pretty well. LOL!
You're obviously an experienced dog owner, is there any kind of specific info that you're looking for? I think they're great and can yak all day about them.
