Stealth requirements (and SF) is the only reason thats the case. without SF its 45 energy vs 60 energy, which could come farther into play (really 75% chance of 35 energy) but with SF, its as i stated.
the whole reason that the theoretical ability generates a combo point is due to the fact that ambush generates 2.
but yeah, thats what i was trying to get at. its no competition. if i could spend (75% chance) 10 energy to get 1 CP and ~60-80k damage.. i'd do it in a heart beat. thats the difference between the two openers (energy capping not as considered, its 3 seconds from application to tick, i wont usually be energy capped 3 GCD after the first hit)