They are making a new review of the DS-X... it is not as good as everyone promoted. The NinjaDS is cheaper and has the same/better features and it has been out for a longer time = has a better support. They even released their fatlib for everyone to get.
I wouldn't say that it has the same/better features just yet. DS-X still has much better homebrew support, can run download play on unflashed DSs and has overall better game compatibility. Also, it
might be slightly faster since it uses built-in memory over microSD. Of course, the Ninja team has been promising to fix all these things in the near future via handy updates, so hopefully they won't be a problem.
Yes, it seems that there is a second opinion coming of the DS-X with a more extended compatibility list to look into all the other issues that were found with it. However, there is still a good chance that those will be fixed in future updates as well....remember, the DS-X is still brand new. I don't think any cart had perfect compatibility before the first update even, so wait for a while.
EDIT : Umm...I'm pretty sure that the GBATemp's staff was contacted and told that it would have microSD support, not have 128 MByte built-in memory. You guys care to clarify?
Also, you guys shouldn't ask which cart to buy before this one is even released, nobody is sure what it will be like yet. It was revealed less than a day ago!