The 1800 does not use the K3 inks. It uses Ultrachrome, but it is the flavor that came before the K3 inkset. Also the 1800 has been out for awhile so the 1400 would be newer technology. Don't know that much about the Claria ink as it is too new on the market. If you want the K3, you have to start with the 2400 or the new 3800 and go from there.
Even beyond that, the 1800 is mainly useful for gloss printing since it has the glop cartridge. If you don't do mainly gloss, then I would consider the 2400 or 3800 first with the pigment inks. The K3 inks are a step beyond the Ultrachrome and IMO, pigment would be my choice. I have a 1280 (dye), 2200 (Ultrachrome) and a 3800 (K3). The K3 inks/technology handle GD (gloss differential--which is what the 1800 glop cart is meant to take care of) much better--depending upon the paper and profile there's little, bronzing is 'gone' and metamerism (since the 1800 is Ultrachrome, it would have a hefty amount of this altho' I don't know how the addition of a red and blue cart affect this) is also a thing of the past with the K3 inks for all practical purposes. The K3 inks are also better in color saturation than the older Ultrachrome. If you print monotones or b/w, be aware that the 1400 is a one black ink only printer---the 2400 is a 3 black ink printer and the K3 inks (plus the ability for the subtle tonality of the extra blacks) do a wonderful job with monos. The 1800 is also a one black ink only printer with switching for the Pk and Mk inks.
I just read the info about the 1400 at inkjetart (basically its the successor to the 1280) [a href=\"http://inkjetart.com/1400/index.html]http://inkjetart.com/1400/index.html[/url] which is worthwhile reading. The projected life of the prints is 98 UNDER GLASS, 200 in albums (dark). The price is the same as the 1280 is now (not when new which was considerably more) so that's def. in favor of the 1400 at $399.99 which is WAY less than the 2400 at $850. I suspect one would need to weigh what you will use your printer for, how important the pigment inks are (do you sell your work, for instance) and do a bit of research as to how expensive the Claria inks are vs. the K3 inks for a 13" printer (also consider the media you will use).
On other forums there are a number of people that state that the smaller Claria printers 'drink' ink--I have no knowledge of this, just reporting what I've read a number of times. Several just stopped using the printers because of this.
I know if I was buying a new printer to use for a number of years, I would only consider the pigment printers (that's what I did when I wanted to upgrade the 1280) because of what I use my printers for but that's a very personal thing that each person would have to consider. They are a known quantity and their output is truly beautiful, regardless of the printer's size but I'm sure the 1400 has beautiful color output also. I would not expect it to be a great b/w printer.