Re: New England Ropes Synthetic lifelines?!?!
The NER WR2 is just double-braided Dyneema, which seems like an excellent choice for lifelines. You get the strength of Dyneema and additional chafe/sun protection by having the Dyneema cover. The only issue I have with this NER offering is the largest size is 5mm, meaning the core is less than 4mm, which does not meet the OSR requirements for larger boats (I don't recall the cutoff, but somewhere in the 35' range and up is 4mm minimum). If you don't care about OSR or for a smaller boat, then this may be a moot point, but the OSR is a good guide for offshore prep even if you aren't racing.
Lancelin, a French company, makes a 6mm Dyneema double-braid with a 4mm core and the cover has reflective strands. That is the route we are taking.