I can only comment on the 5mm, which I have found to be very sharp in my experience with it. Good contrast, pretty comfortable for the eye, moreso than the Delos that I've had and tried. While you already have the 3 and 4mm, because magnification can change so much with these short eyepiece FLs, I think having 3,4,5 would not be redundant. 5 would also give you a more favorable exit pupil if you want planets or the moon to really pop, or if seeing isn't great so you need less mag anyway. Beyond that, I can't tell you if it's right for your scopes, and you may want to jump right past it sometimes, but I can at least say that it's been an excellent eyepiece for me.
I saw my first shadow transit on Jupiter recently with it, going back and forth between my binoviewers (1.7x+9TakAbbe) and the 5DeLite. Magnification was very similar, but crazy enough, the DeLite with slightly more magnification (and a slightly smaller exit pupil) showed a crisper shadow and very slightly sharper definition of the cloud bands. I also thought the Galilean moons looked tighter, rounder as well. I tried to allow for a variety of seeing, but even when it seemed stable, the DeLite did manage to deliver a pretty clearly superior image. What surprised me was that I felt the image had higher contrast with the smaller exit pupil and higher mag in the DeLite. This could be due to the prisms in the binoviewer unit and possibly the eyepieces themselves (which I am going to test individually with a 2X Powermate the next chance I get).
So, in short, the 5mm DeLite is a treat. If it looks like you won't just skip over it, I can highly recommend it.
Edited by jay.i, 16 July 2019 - 11:10 AM.