Id rather just work on one gun that I know is going to be pretty good isntead of wasteing time on others. Empyerean weapons are going ot be upgraded further so I think for me thats the best route.
All Magian weapons have been upgraded from the 75 version to 80 version what makes you think they'd stop now?
Also I hope you're 1) in an endgame type LS/group and 2) the only person in the LS/group who is gonna want the required gems otherwise it will be quite a while before getting the 50 gems.
If you were to get the MAB gun you wouldn't be wasting your time, you'd have the best QD gun until unlocking Armageddon (assuming Mythic isn't an option of course) and the best gun for Leaden Salute.
Edit: Magian system started looking like a great way for casual gamers to be able to get amazing gear with a casual amount of effort and is now looking like another hardcore element if you want the best option. Edited, Jul 3rd 2010 2:35am by Zagen