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The 13mm Ethos and 5x powermate has an effective FL of 2.6mm

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If you're a die-hard planetary observer, I don't think you'll get the performance you want from an Ethos. All eyepieces are compromises in one area or another, and the best planetary EPs trade off FOV and edge correction for razor-sharp on-axis performance.
But if you're not so rabid about your planetary observing, but just want a nice view of everything, it's probably a good idea.

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All optics are a compromise in one form or another.
In the '60s - '70s a wide field eyepieces was ~70°. Unless you purchased one of the expensive wide fields, there was a very noticeable difference in detail & contrast between a "typical' wide field and a "planetary" eyepiece on-axis. Over the years that difference has been dramatically reduced. With the advent of new technology in the last decade, the difference between a high end wide field and a high end "planetary" eyepiece is so small; the average amateur, using typical equipment won't see any difference on-axis.
Because the perceived image is the total of the combined light path from the target to the brain, every piece of that light path plays a role in the perceived image any given individual sees. In forums like this people often forget that everyone “sees” slightly differently.
IMHO the technology of modern objective and eyepiece optics has advance to the level that the person using entirely very high end equipment is limited by the atmospheric conditions and their "eye". The vast majority of the time, the atmospheric conditions are the limiting factor and all very high end eyepieces will be perceived as being basically equal by the average amateur astronomer. On the very rare occasions when conditions are excellent+, it then becomes a factor of the observers’ physiology, training, and experience.
There’s not a lot we can do to improve our physiology other than correct gross defects such as astigmatism, etc. On the other hand, people can be trained to become better observers. This takes time at the eyepiece and practice. Optics companies & labs and military have been training observers for over 100 years; something that is infrequently considered or done in the amateur astronomy community.

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Clear Skies, Bill

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