terminally meaning in and of itself, as oppose to instrumentally meaning as a mean to other ends
10 days of connected experience vs X days of disconnected experience? Honestly, I can't compound experiences/values very much in 10 days, so the amnesia doesn't cost that much - somewhere between 11 and 20 days seems reasonable to me.
I know people with severe memory problems, and they enjoy life a significant fraction (at least 10%, perhaps 80%, some days over 100%) as much as they might if they remembered yesterday.
This question gets much harder for 2, 10, or 50 years. The amount of joy/satisfaction/impact that can be had in those timeframes by building on previous days, is perhaps orders of magnitude higher if an agent has continuity than if not.