Is a puppy right for me?

OK, I've been mulling this over a LOT lately, talked with DH, so now it's time to open this up to the general public, hehe. I've been entertaining the idea of getting my third dog (always wanted three) and it would be a puppy. I'm not one of those people that HAS to have a puppy - my current dogs were adopted at ages 3.5 and 1.5. However I have certain breeders and breedings in mind, so this would be a puppy from one of those, not just adding a third dog in general. It would be a GSD, at this point very strongly leaning toward a west German show line.

My current situation is that I have a 4 year old GSD and an almost 2 year old large mutt. We call the GSD the "performance" dog and the mutt the "pet" dog. My GSD is in a lot of training and activities. I have put six titles/certs on her since I got her less than a year ago. Contrary to what my family and friends think, I really only spend maybe 10 minutes a day at home training, but I do attend training at two different clubs 2-4 times a week and we do lots of trials and tests on weekends. She is a working line GSD but did not inherit the SchH drive of her father (almost nonexistant ball and toy drive, which we are now trying to bring out). She is a very "easy" dog, very well-mannered, under control, biddable, a breeze to train. Her only "bad" habit is that she's a spinner (will spin when she is excited about going out, or spins in the kennel when I leave her at boarding). Coke is my mutt and he's the opposite of Kenya. He is very outgoing and social, a very goofy boy that still acts like a pup and needs some work with self control. He knows basic/intermediate level obedience and shows no interest in doing any sort of "work" beyond that, he would rather sit on your lap or play with a stick. Both dogs are good with people (Kenya is more shy, Coke is very outgoing) and so far have been good with dogs.

Our home situation at the time of getting a puppy would be living in our duplex. We have a very large yard, fenced only at the back. My dogs are only outside while supervised. Kenya is off lead and Coke is on a long tie-out (the rotating kind, not a zip line). We pay our landlords extra deposits for each pet. I work full time, but I work a mile away and can come home for lunch. DH will be student teaching and would not be able to stop home, but he would only be working until school gets out whereas I work until 5pm. I do not work on weekends and my evenings are devoted to my dogs. We do not have any trips planned. We do a big summer trip each year but my dogs come along.

If I got a puppy, my plan would be to use a crate to help with house training and also an ex-pen in the kitchen. I would only allow the puppy out in the house while supervised, and likely use some sort of tether to keep the puppy attached to me. I know I would have to come home from work to let the puppy out and also get up at night. The puppy would probably start out in a crate in our room, since our other dogs sleep on dog beds in our room and the bedroom is on the "outside" wall (as opposed to the side we share with the duplex neighbor). This would be my very first puppy.

I am choosing west German show line simply because I've always wanted one. I originally wanted to get more involved in SchH and get a working line, but we are planning to move to another part of the country in less than a year, so I'd rather wait until after we move and I can get involved in a local SchH club before getting a working line dog. With a west German dog, I would train it much like Kenya (agility, obedience, rally, maybe some SchH but not very seriously and not heavily into protection, and I'd like to try UKC or SV conformation). I already have a breeder picked out, someone I have met multiple times and someone I feel I trust. I like to be able to meet the person and the dogs and establish a bit of a relationship before just picking a pup....another reason why I decided against the working line for now (I don't personally know any workline line breeders, but I think that will come if I join a SchH club after we move).

So what do you think? Am I puppy material or am I crazy?