I'm struggling with the concept of a crew having to take off with two completely different plans in their head, depending on what happens between V1 and the DER and then having to decide at the DER to do one or the other
That ought not to present a problem. TO plan is to go to A then to B unless a failure occurs prior to A, in which case we go to A then to C, in lieu of B. However, much easier to have one story to remember in a high workload situation so I'm with you, good sir.
our EOSID policy says where a limiting speed is required to maintain a smaller turn radius maintain the flap setting achieved at the start of the turn
Unless the procedure discloses no requirement for speed control (which would be MOST unusual - other than for nil sig obstacle take offs, ie a positioning procedural turn rather than for obstacle separation), any turn should be considered as speed critical. Flap (sequence) must be prescribed and flown as prescribed to achieve the planned book climb figures. Ergo, there should be no crew discretion required or permitted other than in the case of a further out of left field emergency ... and then you are on your Pat Malone ..
One pegs the flap specified, including the sequence of flap retractions throughout the procedure, and you MUST remain within the prescribed speed band(s) for the procedure. Anything else is a fool's errand. Keep in mind that the speed/radius consideration may be either for rocks on the inside (min speed) OR the outside (max speed) of the turn ...
Unless you have actually designed some of these escapes for tiger country runways (ie you have seen the problems involved in such designs) I would urge considerable reflection and caution. Yes, there are some margins and pads involved .. but, on (frequent) occasion(s), we design with the edge of the splay running up the side of the mountain .. if you move more than planned laterally, it might just be all over bar the shouting and digging of the bodies out of the mud. This is especially the case for close-in turns.
In the OEI situation, PANS-OPS will guarantee you 15' obstacle clearance
Perhaps you might expand on this comment somewhat ?