The concept of using marks to help make future runs easier, is fantastic, and I think future (Skilling) content should try to develop this. The best parallel currently in game is using MLM nuggets to help expand the paysack or getting access to the upper level.
Building efficiency early for future tasks is peak OSRS imo (Like unlocking proper teleports to do farm runs quicker, or completing diaries for the minor QoL buffs).
One thing I might've missed, are these efficiency items tradable? Non-tradable feels more osrs, but I know devs prefer making things tradable for the sake of selling them.
P.S. It'd be pretty interesting to take this concept and apply it to gauntlet to make it more appealing. Just minor QoL updates based on completions (or a point system developed, doesn't matter). Like having more consistency with T3 upgrades, additional time, faster resource gathering by a tick etc.
Thanks! I'm glad you like the concept I am also a big fan of investing in an activity to make it better.
The efficiency items are not going to be tradeable, nothing from that shop is but the Strange Old Lockpick and the Ring of Endurance will be tradeable since they are from a loot table when searching the coffins in the activity itself.
I don't think there are any plans to change the core design of the gauntlet with unlocks but we can certainly keep that in mind for future content if players like the idea!