Klein,
what you are saying is bit strange: Inkjetfly is actually combining their own ink + Image Specialists ink because their own black is not so black as IS black, so you are saying that Image Specialists ink from inkjetfly is better than Image Specialists ink from IS itself. So this doesn't make sense. I think they should reduce the price of the refill ink from $ 139.95 for 9x100 ml to $99.95 for 9x120 ml to make their inks competitive. Then I would give their inks a try.
Similarity between OEM and the refill is not something one should make a decision from, but from the features, advantages and disadvantages. Nobody will prevent you from buying from inkjetfly.com, if you prefer them, but could you first give someone a good reason to buy them instead of saying "I prefer the one that is similar to OEM cartridge".
Something else: the inkjetfly cartridges are quite expensive, mines are alot cheaper.
I just visited inkjetfly.com to see about inkjetfly's comment about the cartridges. In fact he is right about the problem of printer should suck harder after a while, but he is forgotting something fundamental: the cartridge is actually under pressure so the ink is pushed into the printer, not sucked ! So the cartridge must be very sturdy and completely sealed to maintain pressure.
The first cartridges which are depicted on the first page of this topic actually shows the first batch I received, but they are a bit flimsy. They worked flawlessly, but I was worried about the integrity after long time use. So I have them replaced by the manufacturer, because I was afraid of leaking.
The last batch of cartridges are very well built and solid: a huge improvement, not only in material but also in internal design and how it is refilled. I am convinced they will last a long time.
Maybe inkjetfly should think about it's design to make an extra refill hole in the bladder and place a microfilter system before the ink flows into the printer, but this will force you to have some kind of plug on the ink outlet or ink will splash around on your table during refilling. Then the problem with filtering would be solved. So an extra refill plug and then seal the ink outlet hole, which is enhanced with a microfilter system just like their other cartridges for the R2400/R2880.