There's no valuation cap on this note (until a >50M round happens). It is a variation of the standard YC deal, but on some of the worst terms for an investor.(there's no pro rata, preferred liquidation either).

The only benefit for this early investment is the 8% discount. It doesn't feel like a fair trade for the added risk of investing earlier.

All that said, it's nice to be able to have the outside possibility of future return for a donation that supports their mission.