As a main weapon the Vex Mythoclast is flawed, you can't hold enough ammunition, which forces you to go looking far too often. When you have full ammo you have around 30 seconds of damage before you're all out of ammunition, this is only twice what a good heavy machinegun can give. in essence this means that you have to walk waround looking for ammunition all the time, use synth very often or die to get more ammo. If we compare with Atheons Epilogue which on a full magazine can keep on firing for over 70 seconds, 30 seconds just isn't good enoug. Also if you find ammunition on the mythoclast you'll only get 47 ammunition. which doesn't even fill the magazine with the extended mag perk. I have subtracted the reloading time and measured Mythoclast to 6 RPS and Epilogue to 14RPS.