I use high power for high surface brightness planetary nebulae like the Blue Snowball. These bright planetary nebulae take magnification well. High power eyepieces are also useful for splitting close double stars when seeing permits. Gamma Virginis or Zeta Cancri (triple star) would be a good candidate for the new NagIers. I use my 4mm Radian on objects like the Blue Snowball, Ring Nebula, Saturn Nebula, and Eskimo Nebula. On my 15" Obsession f/4.5 this gives me about 430X . The 3mm Radian would put me at 571X. This is close to that 600X magnification limit you were talking about. I haven't tried the 4mm on planets yet because the seeing hasn't allowed it yet. The new 3.5mm Nagler would give me 490X on my Obsession. This would help me see some of the Minkowski planetaries better. These objects also require high power. Hope this helps. Debbie