Never used it. I did save over $50 per cartridge (440ml) by switching to Solaris Inks. Haven't had a single problem...& no flush neccesary. Just start plugging the new ones in and BAM! Instant savings, same quality. This is my opinion on the matter. If you are still in your 1st year, they can't void your manufacturers warranty due to ink change unless they prove the ink destroyed it (which it won't). But if you are in your 2nd year, it's just an extended warranty & they will tell you that your warranty is Null & Void.
That being said, i'm up a creek as far as price for paying a service tech to help me if God Forbid I ever need it.