The type 5 eyepieces with 20, 26 and 31 mm are ideal for short focal length Newtonian telescopes, even on the 20" f/4 stars are absolutely point-like almost to the edge.
The Nagler zoom offers the best possible imaging quality and keeps up with the best planetary eyepieces in direct comparison. And compared to the Ortho's it offers four focal lengths, a wider field of view and a much more comfortable viewing experience.