First off, sunwayman is in no way related or associated with nitecore or jetbeam. Both nitecore and jetbeam are owned by the same company, however.
I have had the nitecore d10, the jetbeam rrt-0, and the sunwayman v10a. I have been missing my d10 for awhile now. I had hoped the rrt-0 would replace it, but I was always wishing I had my old d10 back. I never bought an upgraded d11 because of all the quality control issues they seemed to have, not to mention the several issues I had with my old d10. You can still find current threads of people here who love their d10 and d11s, but they are getting fewer and fewer if for no other reason than qc issues.
I finally got the sunwayman v10a and decided to bite the bullet and get some li-ions as well. Since I had the extender for the rrt-0, I put them in that as well as the sunwayman v10a. The rrt-0 I have has the xpg led. No contest, sunwayman all the way. The rrt-0, which was my edc for over a year, hasn't been used since the first day I got my sunwayman v10a.
I have also stopped wanting my old nitecore d10.
The difference in brightness from the 14500 to the nimh aa is drastic, but I would still prefer the aa sunwayman v10a to any other single aa I have seen or used. If you are wondering whether to go with the xpg or the xml, I guess that is personal preference, but if you have any kind of question on if you will be buying li-ion rechargeables, go with the xml. The performance boost you get with the xml is so much more than with the xpg. Even if I would not go with 14500s, I would still prefer the xml v10a, but that's me. You might be different.
Imo, if you are getting the sunwayman, it would be worth it to go with 14500s. I absolutely love it and I am blown away by how much light comes out of such a little package. Speaking of, it is tiny. I don't know why somebody would want it smaller, because I can't believe any other single aa lights are going to be more than 5mm smaller, and 5mm is not going to be noticeable. Now the rrt-0 is going to be noticeably bigger than the v10a, that's for sure.
Anyways, at this point, the v10a is just the perfect edc light for me. There will have to be something spectacular to remove this from my pocket, that's for sure.