Toner costs much more per purchase than inkjet ink, but each cartridge lasts much longer so per page they are considerably cheaper. Some cheap lasers aimed at the home market do not work out as cheap (sometimes noticeably more expensive than other lasers) per page, but will still beat a 'jet in the long run.
If you do very little printing, then the inkjet will win overall but if you do a moderate amount or more even a cheap laser will work out cheaper in the long run. But if you only do a little printing there is another noticeable factor against inkjets - they tend to gum up if left alone for a couple of weeks so you end us wasting half your ink doing head cleans next time you use it - bringing the cost per page up higher. My last Epson was terrible for this, and it wasn't a cheap grotty model either.
On good photo paper a good inkjet will produce better photo results than a cheap or mid-range laser, often better than an expensive model. But that again brings up the cost considerably, and on normal paper (standard 80gsm/90gsm stock) all but the cheapest lasers will win out these days. And if you plan to print much plain text (letters, documents) again the laser wins (you don't want to use good photo paper to get crisp text from an inkjet when you can get the same text quality on standard stock out of the laser.
There is also the problem of speed. Never trust an inkjet's claimed speed. My last one claimed "up to 20 pages/min" but it couldn't even pass blank paper through at that rate, and its highest speed setting wasn't worth bothering with. That lovely full page photo could take a number of minutes to create - my laser will kick its version out in seconds. I would doubt the pages-per-cart claims of inkjets too, especially for colour output as nth figures are based on colour text not blocks of colour like a chart or photo, much more so than lasers which in my experience get much closer to their rated output per cart.
These days I go with a colour laser, my current one is a Xerox 6125 which I got a good offer on last year (lower price and free toner carts, which brought the effective price below the cheaper units I was considering) and have been very happy with it, and if I want a few more professional quality photo prints I take the files to Boots or Tesco and use their facilities or self-serve printing machines. What I used to do was to have a B/W laser for docs/letters/draft and a colour inkjet for anything that absolutely required colour.
Don't get the cheapest colour lasers as they sometimes have noticeable banding issues in colour output and once you tot up all the consumables (check how long the drums last before needing to be replaced as well as the toner) don't work out a lot cheaper than jets. If you can get print samples of plain text and business graphic (text with relatively flat colour like charts and such) and photo output for any model you consider just to be sure. My Xerox 6125 has decidedly better photo output than my brother's Samsung 310 (though the Samsung's photo output isn't terrible, its basic colour output fine, and b/w output no worse than the Xerox).
Two other points to consider: a laser will be much quieter, but most colour lasers are significantly larger and need more space around them for ventilation.
Personally, I would follow the ink vendor's recommendations on cleaning. According to their own website their product is clean and sterile, and as long as you follow their cleaning instructions you will probably be fine. While I have never used edible-ink, I have had experience working in the food-service industry, and surprisingly most of the 'rules' are common sense.
I would recommend wiping down the printer and the print head after it's last use that day with a mild detergent and a wet cloth, as the sugar WILL allow bacteria to grow, that said I don't recall reading (nor can I find) any studies that showed bacteria to grow solely in food-coloring. The fact is most food-colorings have zero nutritional value and cannot sustain life, their 'expiration' dates are more geared towards quality of color than health.
Unfortunately I could not find any guidelines on the FDA's website, however it should be noted that in general food-colorings (with the exception of a few synthetics) are generally unregulated by the govt. for the reason previously stated above.
If you know your local health departments information, you would be better off giving them a call to see what they recommend, if you're using this in a commercial setting then you NEED to contact your health dept. to see what regulations they have.
sources: my 5 years experience in the food-service industry
Best Answer
I don't think it makes a big difference—the printer caps the printhead when not in use to prevent it from drying out regardless of whether it is on or off. What matters is that you avoid cutting power to the printer, especially while it is busy—this could leave the printhead in an uncapped state which will more often than not lead to printhead clogging and (in severe cases) possibly failure. (Trust me, I learned this the hard way with Epson printers ?. Unlike HP printers, Epson printers tend to treat carriage jams as fatal errors, typically with error codes 0xEA or 0xE8, which require a power cycle to recover from. This results in the printhead becoming uncapped for an extended period of time, causing severe clogging.)
For printers that are not being used regularly, I'd generally recommend that the printer be power-cycled every week or so (though this can be longer for HP printers, up to several weeks at a time) as doing this typically triggers a maintenance cycle that helps keep the nozzles clear. This process does consume some ink, and because of this need for maintenance (which HP calls servicing), inkjet printers are generally best for regular printing. (HP printers are better than most over long periods of non-printing; see this Wirth Consulting study for details.)
Printers generally do not turn themselves on for servicing. The HP PageWide printers do service themselves when powered on and idle; see the PageWide Technology whitepaper for more information.
This HP article on how ink is used contains relevant information on ink usage in printhead servicing.