Bleah, I've typed a few paragraphs and the comp froze. ><''
I'll...try and type them again.

Ok, basically it is this:
Comparing base 20 TS/LM, 10 FO/1 CM and 20 FO/1 CM

34 TS/LM:
1905-2446

24 FO/15 CM
318-323

VS Hell Meph (26850 HP, 50% LR, 25% CR)
TS does 952-1223
FO does 254-258, 256 avg.

34 FO/15 CM:
458-463

366-370. 368 avg vs Meph.

However, FO dmg is per shard. Vs a boss monster like Meph, most of the times 6-16 shards (10 shard avg) will hit.

So the actual different bewteen the two FO is:
2560 and 3680.

Orb is totally worth maxing if a sorc is doing Meph run.

(And that's a lot shorter than what I've originally typed ><'')

By the way, most Meph MF sorcs have less than 100 energy.