The Tele Vue 24mm Panoptic, 32mm Plossl and 40mm Plossl all have 27mm field stop diameters which also happens to be the largest possible within the constraints of a 1.25" barrel. See field stop (mm) column at
http://www.televue.com/engine/TV3b_page.asp?id=214
Any eyepiece with different focal length but with the same field stop will give the same true field in a given telescope. What will change is the magnification and the apparent field of view.
In the three above the Panoptic has a 68 deg AFOV, 32mm (and below) Plossl 50 deg AFOV and the 40mm Plossl only 43 deg. AFOV. The Panoptic view is the most pleasing to most people being wider whereas the view through the 40mm is like looking through a narrow tube. All however give the same true field of view. See formula at bottom of above link to calculate true field of view (TFOV).
Now what you do get with the different eyepieces is a different exit pupil and for an f10 instrument this is important especially when using contrast and line filters as a larger exit pupil helps so the image is not too dim. Dark skies still required and preferred especially without filters otherwise the sky starts getting grey at larger exit pupils
At f10 a 24mm, 32mm & 40mm would give 2.4mm, 3.2mm, 4mm exit pupils respectively.
Exit pupil = eyepiece focal length / focal ratio. Also
Exit pupil = telescope aperture / magnification
You will get a lower power with the 32mm and 40mm but the same true field. I would get the N9T6 and N7T6 next for planets and planetary nebulae. The D8 does give that really nice magnification which on some nights 166x is not enough but over 200x is too much and you will find that for planetary viewing every mm of focal length makes a difference and sometimes you will be between focal lengths. You could get a 24-8mm zoom and use with a quality Barlow for fine tuning planetary magnifications. The Type 6 Naglers are quite small compared to the Delos. It's a pity the DeLites are in the same focal lengths as the Naglers and I believe this was done to complement the now discontinued Radians. Look out for a pre-loved 8mm Radian.
Whatever you choose, enjoy!