I need to replace topping lift - recommendations please

If we're talking of a TL in primary use, surely when sailing one wants it slack, so stretchy or not is irrelvant.

Well there is a limited amount if slack one can have in a topping lift without it getting into mischief, dyneema will (does) give you a very narrow window of acceptable slack.
 
10mm Liros B 0n B on Full Circle, and has been used for both jobs. Main and Man. Double up with a safety halyard such as spinnaker or genoa.
 
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