As a sign manufacturer and installer we get files from all sources, unfortunately these files come from untagged (no embedded ICC profiles) or from software that is un color managed so I thought I would share a recent experience. I have posted the color builds of 202C when converted to different RGB color spaces and then from those different RGB color spaces to one CMYK color space then printed on our Roland. We received RGB files from 3 sources that were untagged but all were to be based on 202C the results of our first test were less than spectacular. I believe the number speak for themselves.
We use an SC 545EX with Versaworks and it is a solid device. These inks do not do light colors very well, they florence (change color sometimes drastically in different lighting conditions). With that said it is a sign printer and the CMYK, LC LM configuration does real well for a very large segment of the work, many times even great quality image work. We never turn it off that I helps prevent clogging, in my opinion white printing is something you need to consider, market and sell allot of it or avoid it, seems to be no in between on that.
Pick media, download manufacturer profiles for that media and stay with that media. I know white printing is interesting but an ink jet is not something you can use sometimes, it needs to,run every day or it runs up costs.