I wonder about this business of delaying the raising of the gear until you assess you can no longer land safely ahead from an airborne situation.
Having read quite a few POH, while there is advice on wotif you have an engine failure at various points on take off - I have yet to find manufacturer's advice which recommends deliberately choosing to delay raising the gear in order to let you throw it back on the deck.
My thoughts are regardless of the length of the runway you should retract the gear after lift off as soon as you have a positive rate of climb - same as jets. This enables quicker acceleration to safe single engine climb speed.
There is always going to be a window of several seconds after take off where an engine failure is going to require a pretty quick decision one way or the other. And if that decision is based on whether or not you have selected gear up or whether or not you have reached blue line, then now throw in your assessment of runway length remaining to plonk it down - wet or dry runway - night or day - seems too complicated to me.
A night take off with gear left down and thus longer time to get to blue line, is fraught with hazard in terms of judging a bunt-over single engine flapless landing with no anti-skid. Not for this little black duck.
Blue line is a meaningless figure as a decision figure. It is best single engine rate of climb and no more than that. It is not a decision speed quoted in any manufacturer's POH. Lose an engine in a Seminole 5 knots above the blue line of 88 knots and you will be unpleasantly surprised how quickly you have done in 10 knots below blue line due to the drag of the failed engine.
Far better to keep things simple and accept there is an inherent risk with light twins if you lose an engine shortly after lift off. It is all about rudder control and that means adequate speed. Just accept that the sooner you get the gear up after lift off and accelerate to a safe speed aabove Vmca the safer you will be - if you are competent. I am reminded of a ATSB report of a Seminole accident at Ballarat (?) where the instructor cut the mixture around 200 ft in excess of blue line but with the gear left down in accordance with the mantra of leaving the gear down until you can no longer land ahead. The student had no problem with the engine failure as he had speed to spare and he decided to continue. The instructor shouted he should abandon the take off climb as the decision point was agreed at gear up. The student hesitated a nano second so the instructor took over, closed both throttles, lost control and stalled in his attempt to land straight ahead. The wing broke off on impact and both pilots were lucky there was no fire.
What a total balls up by the instructor. I leave the reader to figure out who was to blame for a training accident involving to perfectly serviceable engines, two appropriately licenced pilots (student had 17 hours on the Seminole), and perfect weather. The instructor blamed the student for slow reaction!! And it was the bloody idiot instructor that was the direct cause of the accident.