Well it really depends on your template and whether or not you plan on using special moves a lot. If you have alot of the warrior skills wep/tact/anat/bush/ninj/pois/ and more then fine your special moves will be at a lower mana cost then with out them go ahead be an elf thats just fine. But with the JOAT human bonus If you dont have all theses skills at gm or better humans will still get the mana relief from the 20 points in each adding up in the totals.
Now the real benifit from being an elf isnt haveing extra mana noo no its adding that int to your dex instead and keeping the mana the same! Now thats a good benifit so long as you have enough points in your warrior skills I think the trade off is around 400 points. If you have 399 points then stay human if more then its extra elven dex! (not mana)