I take my previous comment back. The frame would be the most important and safety factor for any bicycle. The thing is i never had any issues with frames in the past. Maybe, it's my luck, but I also dont jump around and pull stunts with my MTB, so that may be thats why it lasts...

Here' my frist Wally world MTB (roadmaster by pacific cycle). It's a steel frame. My GT Zaskar wont be able to compete with this frame in the durability department, but this weighs a ton...