Is it ok to leave a harness on full time ?

It can't be comfortable for a dog to always be wearing a harness.

My coonhound often wears a tracking harness for walks, but he also has a flat collar that has all his tags on it. I take the harness off and on, but leave the collar on. Okay, actually I don't really leave the collar on all the time because I usually uncollar the dogs after their evening walks so they get some "naked time" but I don't have to. I'd just keep a thin loose collar on the dog full-time with tags, and take the harness off after walks.

Ooh, Lupine's designs are so pretty, I love their stuff. []
 
When I used a no-pull harness on Russell he wore it all the time except when he went to bed. Part of that was he was a puppy still being housetrained and we wanted it to be easy to snap his leash on at a moment's notice. But no-pull harnesses are actually quite loose around most the body, that regular harness won't be. I would watch her to see if she scratches at it or if it seems tight when she's trying to relax. You could always have her wear a flat collar too and keep the tags on those. By the way, I don't want to rain on your parade at all, but regular harnesses may actually encourage your dog to pull on lead because it gives them even more power & leverage. You can certainly still train a nice loose lead walk on it, but just be aware of that factor.

I like jones' idea about using a flat collar, too, and keeping the tags on that.  If you want a no pull harness, the Easy Walk is your best bet (www.premierpet.com) but it should only be used for walking, not left on.  The other harnesses are cute, but may encourage pulling.  Check out this site for some suggestions on loose leash walking:
www.clickerlessons.com

I love the clickertraining site - I'm going to be spending some time there
Her harness is fairly loss and she's actually scratching and pawing less at it then she did with the buckle collar (go figure - maybe she's just getting used to it and she'll start the scratching at it once she realizes that its not going to hurt her).   She really didn't like the buckle collar and was always bugging at it.
On the pulling - I know the harness won't "cure" it - the change was due purely out of concern for her neck.   I'm hoping the training will cure the actual pulling itself - she does seem to be doing it less (or maybe thats just wishful thinking on my part !). 
I'll continue to watch her and see if she seems uncomfortable in the harness.  Perhaps when her fur grows in some more I can switch the tags to a flat collar again - and if I'm REALLY lucky she'll also not be pulling by then, in which case the harness will be a moot point.
Thanks for the replies !

I also agree that a collar + harness is the best bet. I leave a very loose plastic-snap collar with my dog's identification tags on it on almost all the time. The halter can be a little tighter (so the dog doesn't pull out) but for the dog's safety and comfort I'd really only leave it on when you have to.

That said, right now I'm keeping my dog's harness on 24/7 because he's wearing a plastic e-collar to keep him from licking neuter sutures and putting the plastic lampshade hat on and off is a real PITA. Still, I acknowledge the saftey hazards (it getting snagged on something and stuck, him getting partially out of it and choking himself, general skin irritation from the halter rubbing him too much...) and keep an eagle eye on him to watch for any problems.

Leaving it on all the time will rub her hair off and potentially, rub her skin raw.  It's better to train her to be still when you're putting it on.  Keep a collar on her, the WhitePines ones are nice because they don't cut the coat or rub the skin.  I use those on all of my dogs.