I bought a number of (Denver) Redfields in the 1960-1985 time frame. They are indeed very good scopes and possibly better at one time than Leupold (IMO), or at least their reputation was equal or better. Excellent optics (for the time), excellent customer service, and very durable -- they just last and keep giving service.
Currently, I have two 2.5X, two 4X, two (2x7X), one 6x18X and one 1.75x5X. They all work well and the lenses are clear. Of course, they lack today's better optics and multi-coated lenses, but I like them.