[casstony]

Hi Craig, trying eyepieces before buying is always a good idea. You might find the 17mm ethos doesn't have enough eye relief for your preference, or you might find the 17mm nagler doesn't have good enough edge of field performance, etc; buying second hand is a good way to go if you can't try a particular eyepiece so you can sell at minimal loss if you don't like it.

Since this is your first fancy eyepiece purchase I'd recommend you target the shortest focal length which you can almost always use; that's likely to be the 17mm or 13mm depending on your local conditions, and that eyepiece will become your most used deep sky eyepiece.

Personally I have my eye on the Delos (high performance and comfort) range when they release the longer focal lengths, but by that time our dollar may have dived and prices may be much higher. The Delos would be well worth looking into for your shorter focal length eyepiece - they're getting favourable reports in comparison with Pentax XW's, with the 10mm and 7mm XW's being two of the best eyepieces money can buy.