It's important to remember also that eyepieces are not "stand alone" hardware. The performance they deliver is very much dependant on the telescope they are used in. "Classic" designs, such as orthos and Kellners, work best in long focal-length instruments. The extremely short F.L. lightbuckets of today require more advanced designs to achieve full field correction across a wide FOV. Coma is inherent in fast f-ratio objectives and if you don't use a coma corrector, the eyepiece alone has to be able to deal with it. Much of my observing these days is with long f-ratio, small refractors and my trusty f/8 six-inch Newtonian and f/10 C-6. Orthos and older design eyepieces work very well with f/8 and slower objectives. The smaller apertures I typically use for backyard observing sessions (f/12 to f/20...for reasons I can explain if anyone is interested) also mean that eyepiece throughput makes a big difference. A multi-coated ortho or Kellner will pass more light than a modern eyepiece with 6-to-9 elements, even if it is multi-coated. More glass means more absorbtion and less throughput. Read: dimmer images and lower contrast with smallish objectives. A huge mirror will shrug-off the few percent of throughput loss with a modern, wide-field, multi-element eyepiece. A small refractor can't afford the loss, and the wide apparent FOV is rarely needed. It's a personal aesthetic issue much of the time. I've made and used a lot of eyepieces. There's more to it, but that's the gist of it. We can get into what is needed for a larger FOV in classic designs, if anyone is interested in making your own eyepieces.