[Renato1 (Renato)]

Hi Drew,
If your telescope doesn't give good views of the planets after you've given it a couple of hours to cool down outside, you probably either have a collimation problem, or you are looking over someone's house with their heater going.

Before they developed multicoatings, Huygens and Kellners were popular because they had fewer glass elements and less internal reflections.

Orthoscopic eyepieces give very sharp views, but have a narrow field (around 43 degrees)

Plossls have a wider field (around 52 degrees).

Erfles - the first generation of wider angle eyepieces. They distort at the edges.

Naglers have an 82 degree field and are sharp across the field. Other brands of 82 degree eyepieces may be on par, or get soft towards the edges, or distort a lot at the edges (and where I mention distortion at the edges, the distortion is always worse in an f/4.7 telescope)

For observing DSOs at a dark site, especially galaxies, an exit pupil of 2mm is often the most recommended (and I agree). In your telescope that means f4.7X2= 9.4mm eyepiece.

Especially for a dob that one is pushing around, I suggest getting an eyepiece as close to 9.4mm as you can get, with either a wide angle or ultra wide angle field of view, as it makes it much easier to track the object manually.

Anyhow, you have a good array of eyepieces already, and you can check out the views of DSOs in them before deciding whether you want a wider field of view eyepiece.

Your 5mm Radian gives 240X in your telescope. That is not a high power under good conditions (when the stars aren't twinkling). You should be able to go much higher than that (though that's where another ultra wide angle eyepiece would be handy when pushing a dob around).
Regards,
Renato