I'm looking at this CIS system for the my HP B8550 printer: CKCCIC PrinterMate Bulk ink system (sold by computerknow).

I e-mailed the seller, who seems to have a good reputation, and asked if the system was leak-proof and if it used non-sponge cartridges. He replied,

"The cartridges have sponge. Non-sponge cartridges are leaky...Yes, the system is leak-proof, and the guarantee is 5 years."

I've never heard that before, implying that the sponge cartridges are better. Thoughts?

I also asked the same question of the guy selling this system, but haven't received an answer yet (it's only an hour after I asked): CIS FOR HP B8550 B8553 B8558 #564 PRINTER CISS (sold by inksmarts).