I have an Epsom 3880 which I guess is supposed to be one of Epsom's least clogging printer but I also live in a very dry climate. My intention was to at least make one 4x6 print every week or two, but in the end I have left it for 4+ weeks without problems.
One thing I do though is to cover it with the plastic it came in and place a cup of water with it under the plastic. The idea being with the dry climate here, that would add some humidity. Obviously I have not done a scientific test, but I have not had problems.
However, I would advise with any printer that you try to make a small print every so often, at least every couple of weeks if you can. But I DO think that clogging is a pretty big deal, it can be insanely frustrating. So if you don't think you can be bothered to print reasonably regularly, then I would go for something that is least likely to clog and not worry about things like droplet size or ink type. I think unless you are doing galery-quality work that is going to be nitpicked, you'll be hard pressed to see a difference. I could be wrong, that's just based on using a few different printers and outside printing companies. Some quote a much higher density of dpi/resolution or number of inks with marketing hype and personally I really can't see an appreciable difference.
There might also me more differences if printing on more specialized papers - I tend to sick with pretty standard luster/satin type papers.
I'm definitely not a 'printing expert', but I do print quite a bit - I have 16x14 and 12x18 prints hanging around my home and office and have done a number of 16x24s for other office spaces. A while back I started reading all the marketing stuff and went a bit nuts. Now I honestly don't think it matters much. Again, specialized papers and subjects, maybe if you are printing for a University class or something, with a professor examining small details, someone would notice a difference, but otherwise... meh. If you are just printing to put on your wall - or someone else's - and just want the prints to look good then I don't see the differences.
Unless someone can show somehow comparisons of the differences, but I have not seen anything. Even Epsom for instance, doesn't show how those new P400/800 printers are so much better than the old printers. Since they are no longer selling the 3880 for instance, why not demonstrate how much 'better' the new printers are? As far as I can tell it is because the older printers were already great as far as print quality is concerned and the rest is details or features. For instance, the P800 'only' have 2880x1440 dpi vs 5760x1440 for the P400. Why? My guess is it make no difference you can see, but 5760 on a 17" print would just take too long where as it sounds so much better so they use it for the 13" printer.
Like for instance this reviewer of Canon 1000 vs Epsom P800 from PC mag:
Unlike the PRO-1000, which comes with 12 inks (well, 11 inks and a clear coat), the SureColor P800 uses nine (Photo Black, Matte Black, Light Black, Light Light Black, Cyan, Light Cyan, Vivid Magenta, Vivid Light Magenta, Yellow). Like the PRO-1000, the P800 comes with several shades of black ink, which, among other things, help produce stunning grayscale images. Granted, the more colors in the palette for mixing, the wider the color range, but frankly I didn't see any real quality differences between the P800's output and that of the PRO-1000. While somewhat different here and there, grayscale and full-color images from both sources looked outstanding, although the Canon model's grayscale images did look a little brighter and more detailed.