I assume you are talking about Baer's Premier II and hard chroming the entire gun...
On the plus side - A hard chrome job will definately make the gun more rust resistant... Although the bluing is very deep/rich on the Premier II, I know that the same durable high quality steel used from the frame, slide, parts, etc. also makes the gun more susceptable to rust... I used to own two (2) Premier II's, and I never had a rust problem with the standard bluing. But I did take very good care of the gun (basically babied it).
On the negative side - Hard chroming does cost extra, and the gun is already so expensive... Even with a matte hard chrome job, there is more glare from the top of the slide when shooting outdoors on a sunny day. The Premier II comes with a matte bluing at the top of the slide to cut down on glare, and it is pretty effective. Also, some people just don't like the look of a white/silver gun...
In the end though, it really is up to you on how you want the gun to look. My opinion would be to order the gun in a standard blue. If you have a problem with rusting, then you can always send the gun out later for either a hard chrome job, or teflon, or nickle, etc...