For planetary, definitely try removing it. It wasn't designed for that purpose, and I've heard stories where it generally flattens the field but you lose a little sharpness and contrast. IMO, throwing money down for a shorter focal length Nagler to use with the (cheap) reducer screwed on is throwing good money after bad
Just take the reducer off and you get pretty much the same magnification from your 11mm. 2 minutes saves you nearly $400
For the majority of DSOs that will fit in your current setup, they'll also fit in the FOV without reducer (of course, there will be some exceptions). For the others, use the reducer, if that's what makes you happy
The C8 is not a wide field scope...but there's plenty of options for getting wide enough for most things without reducing aperture, contrast or sharpness. Look for a SCT diagonal, such as the GSO or Bintel one, it screws directly on the rear thread to keep the focal length under control.
The light drop off is an interesting subject, and in theory the 38mm baffle tube diameter should be more limiting than it appears in practice. I use an eyepiece with a 46mm field stop and I've not noticed a dramatic light fall off...just as wide a FOV as my scope can give. An SCT can show a little coma right out toward the edge but it's pretty minor. I don't recommend you go looking for it, as you can never unsee it afterwards
Another way of looking at it is that if you only ever use the 1.25" for wide, you are cutting out a large proportion of the light because 38mm baffle tube is larger diameter than 27
The Omni is an OK eyepiece...an upgrade to a TV plossl is going to be fairly subtle, and especially with the reducer you may not notice any difference.
The 24mm Panaoptic is a lovely eyepiece but not perfect. Have a read of
this review and decide if it's for you. The Meade and ES equivalents can be found for a lot less money (about the same as the TV plossl). A 35 or 41mm Panoptic or 40mm Paragon is a better "wide" solution for a C8...IMO
The Baader Hyperion Aspheric work well at f10 also and are less expensive, as are the ES 68 or Meade SWA equivalents (but they're a lot heavier than the Baader)
Regarding the weight, you can easily shuffle the scope up through the clamp a bit so it can still clear the base and balances the scope better too.
I avoid the faff mid-session through target selection and planning, by only taking it off/putting on once (if at all). The next few months for me will be heavily dominated by planetary and so I probably won't use it again until winter comes
But try it and see for yourself
and please report back. Ideally choose the same object under comparable magnification with and without the reducer. 47 Tuc might be a good candidate although it's starting to get a bit low in the sky now.
Ultimately, if you're worried about width of field combined with image quality, you might be better off channeling the money into a short doublet refractor...a 100mm at f6 should fit just fine on the SE mount and will give you more than double the FOV you can get from a C8.
Btw, I'm not dissing the C8 at all...it's my favourite scope...I have two