I red the same things and it seems you can choose to run a game in pal or in ntsc. In fact even a pal game on a pal dreamcast which normally run at 50 hz (not every pal game has a menu to choose either you want to run it in 50 hz or 60 hz mode) could be played at 60 hz if you choose ntsc in the menu.
I'm waiting for mine to arrive to test it with Grandia 2 (pal) on my pal dc.
Yes DC-X is the best choose to play imports on DCs. I have one and works with all of my imports (25-30pcs), while the modchip that i use before dont run some from my stuff. If you press the A button while the disc boot, you reach the options menu where you set the 50/60hz the video outpt and other things.