I'll go ahead and throw my .02¢ in, this is of course all based on my experience and my opinion - FWIW...
I run both a 1204 and 1604. The 1204 I've had for 3 years, the 1604 I just bought used this spring. Both of them are shut down every night, weekends and when not in use. The 1204 ran OEM ink for nearly the first 2 years of it's life. However, both of them are using a bulk ink system. (I save enough on average to make my truck payment every month vs. using OEM.) Typically they each run anywhere from 1-8 hours every day. However, sometimes during slow periods, I may only use 1 printer and not the other. At this point, I have little fear of leaving a printer off for 3-5 days. I would get a little antsy beyond that, but I would be downright worried if left off for more than 2 weeks. Not because I feel it couldn't be saved, but I know the amount of work you typically have to invest if you leave your machine off and the head starts drying out.
Again, this is my experience talking only, but I have found the eco-solv inks to be very forgiving in comparison to mild or full solvents. I've left both printers off for several days at a time, during holidays and weekends with no ill effects. In truth, I may come in and find some missing nozzles, but usually 1 or 2 quick cleans and they're back up to full status. Even if not, I have used other methods to clean the head that most wouldn't attempt. But sometimes desperate times call for desperate measures - and at some point you have nothing to lose and everything to gain.
I MUST STRESS, I have found the most important thing to ensure these ValueJets print properly and minimize losing nozzles is to ensure a regular cleaning once or twice a week around the head, around the capping station, and keep the drain lines clear of clogs. In addition, the CONDITION of the capping station and it's ALIGNMENT are CRITICAL to a properly functioning dx5 head to not lose nozzles while sitting idle. If you don't have a tight seal around the head, even if just on one side, it will cause you nothing but headaches - even if the printer is left on and in doing auto-cleans. I strongly advise to replace your capping station every 1-2 years even if you think it doesn't need it. Once problems arise, they can snowball quickly.
In the end, much will come down to whether you are comfortable working on your machine at the mechanical level and if you are willing to do what it takes to keep it running.