Rory, I'm no expert but I'm thinking that is a hell of a lot of line out on a 3wt. "Only get like 60-70 feet," How much do you want to get out and where would you use a 3wt that you needed more distance?
And the reason i think my 3wt is more accurate is just the rod fits my casting style better, its my favorite rod and i have the best feel for it. i have it longer than my 5wt and use it whenever i can. I just use the 5wt on lakes where i commonly need a 70 foot cast.