Best way to know is to ask supplier for a small amount of sample solvent to test for impurities (usually will oblige with free sample since want to sell more in future), and run a blank run and compare to the higher-grade solvents when you have run these as a blank run, to see how many extra or larger impurity peaks you get. If you can live with this (since won't interfere with your separation & analysis) for the lower cost then I say hey why not?