I think the rewards system should cover all the diff use cases and not just LPing, otherwise sponsors have little reason to do more than minting and LPing:
minting and trading away the synth (shorting)
adding liquidity without being a sponsor
holding the synth without being a sponsor?
For non YD products, someone that bought the synth and is holding to it betting on it’s price is as much of a “UMan” as an sponsor, the system needs both.
For YD products, I would also consider delegating the LPing rewards to curve.fi, but that’s something to discuss in another topic: Proposal: Using curve.fi metapools for synths pegged to ERC20 tokens