I think the idea of refurbing existing rides is a great idea. I remember going to astroworld after Serial Thriller and Texas Tornado were installed, Batman, and the other coasters were looking pretty shabby. Although they did get a new coat of paint before the end, I think the existing rides should have been priority over just getting somthing new.
A new coat of paint can do wonders for the look of the ride and the park. The majority of park goers, are not coaster experts, most do not know the difference.