I would suggest trying to set up a schedule of printing something, even a test print on cheap paper, once a week and see if that helps. After a while, vary it to even more frequently, or less often, depending on your results.
Only if that modest extra expense and inconvenience doesn't solve the problem, then go for the 3880.
I've never used a 4900 myself, but my elderly 3800 goes for long unused periods with no clogs. Only when a fresh print looks funny, about once a year, do I even bother with a nozzle check and a head cleaning. My 3800 is almost always covered when not in use, and is kept year-round between 65 and 70 degrees Fahrenheit and between 30% and 50% relative humidity.