The Tele Vue 17mm Type 4 Nagler is a 2" eyepiece whereas the 16mm Type 5 Nagler is 1.25" and there is a big difference in weight and size with the 17 being the heavier and larger of the two.
I would not recommend the 17NT4 with Barlow just to get higher power since for this combination to work without compromise you would need a 2x Powermate and this adds more weight to the point where you may have balance issues if your altitude bearings are light and smooth in action. A Tele Vue Barlow would be a bit lighter but the Powermate has the advantage of allowing the eyepiece to perform exactly as it was designed, i.e. no extension of eye relief and no vignetting which is more of a problem when barlowing longer focal lengths or eyepieces with already long eye relief.
The 16mm could be used with a Barlow or Powermate but note Tele Vue only has 2.5x and 5x Powermates in the 1.25" size. You can of course use the 16NT5 in the 2" Powermate with an adaptor.
The 16NT5 or 17NT4 by themselves in your telescope would give you about 75x and a bit over a 1 deg. field which is nice (assuming f5). However it is a power for say large open clusters, eta Carina, Orion Nebula etc. Globular clusters such as Omega Centauri or 47 Tuc can do with a bit more power that say a 13mm eyepiece would give on your telescope. You mention Ethos so I will compare the 13E to the 16NT5 and the true field is almost identical since the field stop diameter is almost the same. You simply get the same true field at higher power and wider apparent field.
See
https://www.televue.com/engine/TV3b_page.asp?id=214
The Ethos is a very fine eyepiece with excellent transmission but the 100 deg. field is not for everyone and I urge you to go to any (Covid safe) star parties and look through as many eyepieces as you can to see what YOU like best. When I looked through a 13E or 8E I found myself looking around too much giving me a bit of eye strain but if looking at the centre, the field stop simply got out of the way. My personal preference is for the 82 deg. Nagler field particularly in the Type 4 series. Note eye relief of the Type 4 Nager series is good for eyeglass wearers if this is important to you. The eye relief of the 16NT5 is fine (at least for me) for non eyeglass wearers because of the volcano top design.
I would still recommend getting the shorter focal length you desire in a single eyepiece with your choice of apparent field as there are many to choose from.