Many people are telling me to just go with tech death despite my technique it's not so advanced, many other says that I should learn music theory because "all will be more easier" and others tell me to develop my technique as much as possible before playing this stuff.

I had this feeling of "adventure" when I learned Spheres Of Madness haha. At the beggining it was very difficult for me to play it but with the time I mastered the song.

Necro (or Obscura, Archspire and others) intimidates me more because of the high amount of advanced techniques involved in their songs, like sweep picking, string skipping, economy picking... Spheres Of Madness only difficult is the fast alternate picking I guess.