Will it work?
Short answer - Yes.
Long answer - Most likely it will work out of the box. The DSTWO works on every DS console and firmware produced to date. If you put the card in, and after installing the necessary EOS files onto your microSD, the cart fails to start (black "An error has occurred..." screen), you can download the latest firmware update file from the DSTWO website, rename it from dstwoupdate.dat to dstwoupdateb.dat (note the extra "b" in the filename), place it on the root of the microSD along with the EOS files still, and launch the card. The card will error out again, let it sit on the error screen for five minutes. After five minutes have passed, shut down the DS, remove the DSTWO, and delete the dstwoupdateb.dat file from the card, then try to launch it again. It ought to work now.
I'm not sure if they have the DSTWO updated to the latest firmware or not. If you're concerned, it wouldn't hurt to email them with your order number politely asking if they could update the firmware on the DSTWO if it hasn't been packaged and shipped already.