I'm unfamiliar with the zoom eyepieces your thinking of, but do note they have a very small fov.
I have owned a few of those and used in my 12" dob for quite a while.
27 pano .. very comfortable low power eyepiece , lots of eye relief
and great views , heavyish but not overly so. I didn't have to mess
with couterweights to much when dropping to higher powers.
16t5.. eye relief is very tight with this one .. (why I sold it)
not loads of info about this one around.. I think its a great eyepiece
very sharp views , compact and that great widefield view.
13t6..lots of info out there on this one for good reason.. its got a lot going for it, compact , great wide views and a power that will live in your focuser more often than not.
I sold on the above two because comfortable eye relief has become an issue for me more recently.
14 xw .. lots of eye relief and excellant views, not as compact as the 13 t6 and of course it dosn't yield that ultra wide fov . I wanted top stay around this mag and this one fits the bill well.
8.5 xf.. I noticed when I finished my 12" that my 7 nagler just wasn't getting as much use anymore.. the xf does.. its one I can generally drop in the focuser and get some use of most of the time
great pentax views ,a little narrower fov ,very light and priced very nicely .
I am still hanging on to my three eyepiece policy and there are definately other options but for me in a 12" f5 these work out just fine
good luck with your choices ..its only money.. you'll forget how much these pricey bits of glass can take off you soon enough
