I have a RimX. It is not perfect, but I have so few issues with feeding and ejecting that I am inclined to believe it is from short stroking the bolt, etc. I bought a barreled action from Curtis Custom Weapons in MO and bolted it in an ARC XYLO. I made the mag height adjustment per the instructions and the thing just runs. I have seen people have issues though.
As far as accuracy, I don't know that I could shoot anything any better. It will routinely shoot under 1/4" for 5 shots at 50 yards for the 3 lots of sk standard I have put through it. The only other ammo I have tried is some sk semi auto. It does not shoot well. More like 1-1.5 moa with the occasional good group. I have not shot a lot of paper past 50 yards, but I have a 3" wide by 5" tall diamond at 203 yrs. It is pretty easy to go 10 for 10 from the barricade with the sk standard plus with a good wind call. When the target is freshly painted the 10 shot group appears to be close to moa even at 200 yds.
I have not shot any better ammo than sk standard plus through it. I have not seen a need to spend more money on ammo.
I have shot with several guys shooting vudoo rifles. Their guns are definitely accurate. I have played around with a couple briefly. The feel of the action is not quite as good as my rimx but that could be due to how they are timed to the individual trigger in that gun as well.
I honestly don't think you can go wrong with either. There will definitely be a higher probability of issues when mixing and matching chassis/stocks/bottom metal with the rimx unless assembled by a good smith. The 22lr is more finicky than centerfire in my experience. Also, the magazines for the vudoo are less expensive than the rimx magazines.
I honestly love my rimx, but was ready to buy a vudoo and was talked into a rimx by my smith. I have several Zermatt centerfire actions and felt confident in them and their customer support. I am also a sucker for a smooth action and was told they feel a little smoother than a vudoo. I also really wonder what a vudoo with the trigger timed would feel like. A lot of people I speak to about trigger timing don't even understand what it is. It can make one 700 clone feel like shit while another one feels great. In reality, if both triggers were timed to the action well, they would both feel similar (I know not always the case).
Honestly, the RimX is a lot more of a wildcard depending on the build components and the smith. The Vudoo is a complete gun and it will work. They also have a great reputation for customer service if you were to need help with something. I think there are pros and cons to both. It is hard to tell you which is better for your own personal situation. If you have the means, maybe buy both and sell the one you like the least. If not, I would say a RimX built by a good gunsmith is equal to a Vudoo. They will both be very good. Most, if not all, of the problems I have seen from both actions have been people trying to build lego rifles and having feeding issues or barrels that were cut wrong for the rimx.