You sure about that?
Assuming HT buff:
HT-ROT (3 targets): (170+150*3)/(70+120)= ~3.26 DPT, 310 DPG
CT combo (4 out of 10 CT ticks): (180+220+160*1.11+20*4)/(70+60+60)= ~3.46 DPT, 219.2 DPG
FT combo: ((150+200+300))*1.11/(70+60+60)= ~3.42 DPT, 216.7 DPG
CT combo (10 out of 10 CT ticks): (180+220+160*1.11+20*10)/(70+60+60)= ~4.09 DPT, 259.2 DPG
FT combo (Dis. debuff): ((150+200+300))*1.11/(70+60+60)= ~3.80 DPT, 240.5 DPG
It seems like all CT/FT combo variants are superior per TP (for 3 targets) and if you're aiming for damage/global for bursting (BfB, etc.) you may as well use 3-target DS (3 DPT, 480 DPG).
I tend to use DS for 4 targets as well because the DPT difference is insignificant:
HT-ROT (4 targets): (170+150*4)/(70+120)= ~4.05 DPT, 385 DPG
DS (4 targets): (160*4)/(160)= ~4 DPT, 640 DPG
*CT Combo's DPT surpasses both at the full 10 DoT ticks only.
the exception being when I have to make every TP count of course (REALLY bad DPS, low TP, etc.) The general rule of thumb I follow is to alternate between best DPT and DPG rotations. DPT rotation for most situations, DPG for when I'm buffed (BfB) and to prevent myself from over-regening (=> wasting TP=> wasting damage potential) between pulls.
I agree with everything else, though.
edit: fudged Disembowel's potency, and yes meant potency in all cases of damage