Sheriff is a curser which can only curse so many times. It would be okay to overpay

because an average Witch curses about 3 times (please correct me if I'm wrong). Afterwards it's just a terminal Silver which is cosidered worse than a Witch that doesn't curse anymore. Buying subsequent Sheriffs will often seem like a bad idea although buying a late Sheriff for

, if you expect it to curse only once before the Curse pile runs out, has a low opportunity cost which is good. Unfortunately, Sheriffs that have done their job make poor targets for trash-for-benefit. Most other cursers are probably better. So all in all, Sheriff is a relatively weak card but it has a unique and interesting design and another application of the overpay mechanic is always welcome. I like it.
Conserve enables players to convert every

they can spare in a turn into a coin token. Usually you wouldn't do this more than once a turn because otherwise you could have bought a card for

. It might be very interesting in the endgame though, when

-cards are useless to you and 2 coin tokens would give you the chance to score another Province next turn. So this event might totally work out.