Rockcreek- I don't think that it makes much difference for allergies. For some reason, Ester-C seems to be especially effective for helping arthritic joints, although most of the studies I read on that were on dogs, not humans.
My own experience (not having allergies personally) is that taking more than a couple of grams of any form of Vitamin C daily "dries me out"- my nasal passages and sinuses get quite dry, uncomfortably so. It might be if you had allergic post nasal drip that would actually be a boon.
One interesting thing we've noticed over the years is with hubby, who has/had terrible hay fever- ragweed allergy. Being a farmer, that's not a great problem to have in the summer! But we found that once the bell peppers and then canteloupes in the garden started ripening (and we started making pigs of ourselve on them) every year, his symptoms would pretty much vanish! We suspect it's the Vitamin C content, but it could be many things, including Vitamin A and bioflavanoids. Whatever it is, it has repeated over a decade now, and he's long since stopped bothering to take any prescription antihistamines, and only very rarely even needs an OTC anti histamine. Interesting, eh?
Summerthyme