Well to be honest I don't think there is such a thing as 100% security from bricks when it comes to 3DS flashcards, using Gateway is as safe as it gets ^^
MT pretty much announced it on their website, they uploaded a video with GW3D displayed in the settings....they have since removed the video and reshot it to hide it, but it was on their site for a whole day....but thats as close to an admission you will get from themI doubt MT Card is going to announce that they use the gateway firmware if they do use it, I agree that Gateway is currently the best bet for not bricking your console.
is it present on the mt-card? I want zero risk of bricking... Shipping is ultra expensive for me... I can't afford sending my 3ds for unbricking if it bricks.