I have heard of people doing it successfully but as a tech I have to give the paranoid answer. The major concern is that you might put too much pressure into the new cartridge. This will put more pressure on the whole ink system. One outcome of that could be that you leave for the day, a small amount of ink gets pushed through the head due to the extra pressure, creates a siphon and empties all of your cartridges. Not only can this cause a huge mess, it can damage your machine. If that happens, you just lost all of the extra savings. If you think you are going to save a enough money to make up for any losses that you might incur, do it.
Side note: Having ink left in the cartridges is generally a
sign that your maintenance station is failing. These ink systems are extremely dumb and do not actually know how much ink is being consumed during printing or maintenance cycles. They just guess. When the maintenance station fails, it pulls less or no ink at all but the printer keeps on thinking that ink is actually being used. This causes the smart card to think it's empty before it really is.