Just a couple of things to point out:
speed -If they use a flash chip like what is currently used on removable media, writing speed wont be an issue and it should also work like removeable media (format, FAT etc). Remains to be seen, judging by the pic on their site though it could very well be a high speed chip like what is found inside a MS Duo or SD card. Perhaps some of you have even seen those SD cards with the built in USB connection so they work as jump drives?
Encryption -of the ROM isnt as big of an issue as some seem to think, once you get the menu running/crypted so it will run, you have conrol of the DS and could fuddle the encryption engine so "clean" ROMS can work... if anything one
may have to decrypt the secure area of existing dumps (though that really could/should be taken care of by the loader).
DS cart file system -You all probably have an idea about bankswitching already, how GBA flashcarts use bank switching to make multiple ROMs appear to the GBA as if they are at the 0 mark on the data bus and run properly... well, the same could be done with the memory chip on the DS - I really dont see why it couldnt be done also with a TF card or an onboard flash.
To me those are the obstacles that would need to be overcome to satisfy the most picky buyers... not too many, hey?
What it will really come down to is quality. The hardware build quality (which IMHO seems pretty decent by the flash pics). Also, the quality of the software/updates being the biggest flaw that can cause
any of these types of products to suffer in opinion and thus sales - NeoFlash comes to mind here to me, for "warez users" (commercial ROM users) software complaints are the biggest thing I see day to day,
rarely are peoples problems related ONLY to the hardware itself (though their flasher can be a real pain, normally its problem is still
software related).
If it (software AND hardware) is quality, the
biggest benefit I can see from this is commercial software dev studios having a much cheaper option than the official Big-N writing hardware (the carts arent too pricey, I gather, the writer is though...) to put out in-development projects to 3rd parties for beta testing at a low cost, which, in my mind equals far better quality games to the DS users
Amy rate, if you read this far thanks for listening to me prattle on. I look forward to a "staff review" to see how this one turns out (and have to say too thanks for the warnings about the NinjaDS flashcart - looks can indeed be deceiving)