*WARNING* Keep Element on meks at all times! As long as your mek is out you must have element on it otherwise it will despawn/die. 1 Element per day it is out seems to be enough. I've lost 2 meks with no trace even in tribe log because of this.
Do not fight a level 290 corrupt wyvern with a level 51 primitive Mek. Let's just say they self destruct. 40 element plus other mats just exploded. Thank God for glider suite, that shit blasts you straight into the air when it explodes. Still died wyvern got me on foot. Fml.
At high levels they can output extremely high damage, especially with the sidearm it comes with doing extra damage to Corrupted. You can even fit these things in the caves, however it feels as though they have no damage resistance and can take a lot of damage VERY quickly.
If you already have a Mek or were planning on making one anyway, if they are absolutely amazing at clearing out very large areas of trees. I'm talking can destroy 500 trees in a matter 30 or so seconds. To my understanding this is one of if not the only thing in the game that is not stopped by trees it just goes straight through them like it's not even there