Penury/Parsimony is enhanced by having Conserve MP being 100% proc (this kicks in prior to the 50% reduction). On average, this result in ~36% MP cost instead of 50% without these. The overall savings in MP make these better than Teal Slops (unless MP is not an issue/are not using Parsimony with your nukes).
roughly if you have teal slops the damage difference is these are about -60 damage roughly in comparison to teal slops. if you have no problem with less damage i would recommend these, but if you like higher damage and are less concerned with mp loss use teal slops until you can get these +2