I can't help myself when it comes to eyepieces, I'm a hoarder with multiple eyepieces same FL
I love my Nagler's, the 82" apparent FOV suits my taste for that immersive feel {Ethos little too wide for me}. Looks like you have the plum 12mm,2mm exit pupil, slot covered for the new CFF {guessing that's the scope}. For me I'm not sure I would want to go more then 20-24mm with that FL and aperture , then you have to decide whether you want the extra weight with the a 2 inch eyepiece or with 1.25 {what diagonal type/size do you own ?}. I have the 22m nagler and 24pan, the pan is a workhorse but I would take the 22m nagler despite its weight. Unfortunately I haven't used a Pentax XW, maybe the 20XW is worth considering at that FL range {there was one in the classifieds but it looks like it has sold .......
}. Id go for the 22mm Nagler, your 12mm eyepiece and 7mm nagler/ Pentax 7mm XW/6mm delos or maybe the 6mm Ethos if you like that wider vista........if three eyepieces I would add either a 16mm nagler or Nikon NAV-17HW {-pricey}