Ethically, according the the Code of Ethics (COE) that is set forth by the American Boxer Club (which is again, who creates the blue print of what makes a boxer a boxer) yes, you should spay your girl.
It is my feeling that if this ever changes, it will be a very long time in coming. The ABC *just*, as of last year, made the following alteration to the COE:
Boxers of any color not allowed by the standard. Such a Boxer will be placed on a contract, to be signed and a copy retained by all parties, that includes the following provisions:
1. Limited registration will be provided upon completion of a spay/neuter.
2. The new owner will give the breeder a deposit to cover the amount of spay/neuter. This deposit will be returned upon presentation of a certification from a veterinarian that the procedure has taken place.
3. The breeder may charge veterinary expenses directly related to the puppy.
(This can be read in full on the ABC's website:
http://americanboxerclub.org/ethics.html )
Given this, I would expect to see a change in the COE stating that breeders may charge amounts equal to that of what they charge for colored puppies long before they ever considered granting full registration and breeding rights.
I know that at first glance this seems like the "elitest" point of view, and to be perfectly honest, to some it is. I am of the opinion that whites should not be bred, for the simple fact that experts have determined:
1) That there would be no advantage of introducing whites into breeding programs.
and
2) That doing so could possibly bring with it the chance for introducing deafness in all boxers.
That is enough reason for me to stick with colored dogs, and strive for flashy to plain breedings in order to try to breed to the standard, rather than away from it. Which, IMO, can hardly be considered elitest, as these are very valid concerns that take into consideration the health of the breed as a whole (which ultimately should be our first and foremost concerns with regards to breeding).
I guess my question would be what do you feel the advantage would be of introducing whites into the breeding population?
And more importantly, how do you feel that breeding your girl (regardless of her color) will improve the breed as a whole?
I'm not asking these questions to be trite or elitest, rather the second question is a question that we all need to ask ourselves prior to considering any and every breeding we plan to undertake, and one that I ask myself on an almost weekly basis as I seek out potential stud dogs for my girls.
Which brings me to another thought as well. If your girl is not to the standard, and is disallowable from breeding by the ABC's COE, how will you be able to find a quality Champion male to breed her to?