I have two nigerian dwarf goat wethers now and they are the best! They are smaller like pygmy goats and make the sweetest pets. I don't think the size should matter with the meat goats so they should be good all together. You definately don't want to keep him alone. Goats are herd animals and don't do well by them selves.
Some pros and cons... Pros would probably just be that wethers make really sweet pets and great companions. The cons aren't too bad but sometimes they can be noisy, mischievous, and a little costly. There are also annual shots that they need but I couldn't tell you much about that as I do not know much about it myself. Once my babies turn a year old I'm gonna bring them to the vet and see what shots and dewormers they think I should use and how often. Usual the shots and dewormers will depend upon where you live. Hopefully someone a little more experienced can help you there.
I'm not sure about meat goats, but wethers as pets have a pretty simple feed schedule. My boys get GRASS hay (NOT alfalfa hay!), about twice a day and 1/2 cup of noble goat feed/pellets daily. Make sure not to give wethers or bucks alfalfa hay unless you balance it out with grain. And then if you feed any grain you must balance it out with the alfalfa hay. If not properly balanced, the male goats can get some kind of fatal urinary disease that I forgot the name of. Again, hopefully someone more experianced can help here. This problem however, does not occur in does or female goats. I personally just prefer to feed grass hay and no grain.
Goats also hate getting wet so I would recommend a sturdy shelter than can keep them warm in the winter and cool in the summer and also dry all year round. In the winter you also want to feed a little more hay so they can stay warm. Too much of any rich food however will cause goats to bloat which can easily lead to death if not properly treated for. Signs of bloat include foaming at the mouth, not eating, immobile goats, and very large bellies. You will definately want to read up on bloat and other diseases so you can be prepared for any urgent health issues that will most likely occur.
Anyway I hope I've helped and that it wasn't too much of an information overload!!!
Anyway good luck with your goats! Hope this helps!!!