Actually I'd think that Redmond Real Salt would be (if anything) "weaker" than regular table salt since it has all those other minerals in it, and thus the percentage of sodium chloride would be less in any given weight of salt. I mean, it has all that stuff that turns it pink, for crying out loud! If there is a problem for some reason, I guess you could just use a little less.
I have used the Redmond salt for neti, I also add some baking soda (sodium bicarbonate) as a buffer in a 3:1 ratio of real salt to baking soda.