Hello, thanks for checking in. My writing efforts have been guided elsewhere for a time, but now I can get back to this 
.
First off, no, working with demons will not bring any negative side effects if you approach them respectfully and without fear. The demons want to help you, and they are delighted by seeing you succeed. The demons have historically gotten a bad reputation even within the occult, but this is more due to a misunderstanding of these beings than to their nature.
If you’ve only ever called upon angels, then the thought of working with a demon can be frightening for some, especially if they were raised in an environment that painted them in a bad light. More than anything else, I would stress that the demons want to help you. If they always brought negative stuff to those that called upon them, why would anyone work with demons?
One thing to keep in mind though, is that their personalities and their energies are certainly quite distinct from the angels, and the same approach that one may take to interacting with angels is not very appropriate for demonic work.
The angels, by their nature, are very concerned about the other. They are connected to your Light, the part of yourself that is a reflection of the All. This extreme selflessness has sometimes been interpreted as a lack of free will, but from my own experiences with the angels across a couple lifetimes, I would say that they do have free will, but that, relative to beings of Shadow, they are not very concerned about their own individual selves. They still are, to an extent, and they do have plans that they would like to work towards in the world, but they only like to share such things with those that are very close to them.
I’m not quite as qualified to speak about the nature of demons and other beings of Shadow, the part of yourself that is a reflection of your own Divine Identity, but generally speaking they are more concerned with you empowering yourself. They want you to rely on your own power, to realize that you do not need the help of anyone else, because you are yourself Divine in your own right. To clarify, you are Divine in that you are a part of the All, but you are also separate from that All in a sense, yet still Divine. You could say that you are Divinely sufficient, if that makes sense.
I’ll write more about approaching demons from the perspective of one who has only worked with angels, but I thought I’d put my theoretical musings out first. I could go on about such things some more, but I think the wisdom needs some time and space to unfold, for myself and for those reading.
I’ll also be making a separate post about the Omnipotence Transformation sometime soon describing some of the visions and other things I’ve experienced through the working, as well as some of the effects it has already had on myself and the world. The process is still unfolding, however, so I may wait until after I complete the operation this Thursday.