Unless you are looking for gear that won't be in loot table post patch, there is no point in cashing it in. Some will tell you loot is pre determined. That is true for a DLC. Others will tell you this is an update and so loot is not pre determined. That was true last time when they released eg twilight garrison. The truth is, we have never had an update as large as this before. It sits in between past updates and DLCs in terms of size. The other truth is, nothing will decrypt into lower light post patch than pre patch, and worst case you get pre patch loot at pre patch light, which is what you'd have got anyway. Taking all that into account, I have not been cashing purple, gold engrams in since Friday (managing inventory, vault, postmaster space) and have tried not to push any factions over a new rank. If I did (because I'm not stopping playing just to keep a faction under a rank up) then I've not cashed the package in.