You make some excellent points here and I think influenced @setoshi 's post in this thread Intrinsic DPI Productivity w/ $INDEX as Risk Backstop
I think most of the this discussion has continued in the thread above.
I’m (currently) leaning towards:
INDEX staking for risk backstop / rewards (as INDEX and $DPI / other ?)
$DPI and DPI-ETH LP staking for rewards (As INDEX and $DPI)
INDEX to come from treasury as a method to incentivise staking and distribute INDEX.
DPI to come from the farming.
90 day lock in for both types of staking (mainly because I think it would be simpler to implement)