Colin summed it up well.
The brown dryer with the quartz bulbs and zoning is the only unit I know of that claims to be able to "zone" curing in the chamber for multiple garments and ink types running at once. That's not for us for a number of reasons but it does make that claim if it's of interest to you.
I will say that despite having about as much firepower as you can get in a gas dryer here, when you are running full size wb/dc/hsa prints at 600-700pcs/hr, you probably aren't running anything else down that belt. Belt space : retention time messes up your ability to load two jobs and, ultimately, air exchange rate becomes the bigger factor with all that moisture loading the chamber. As much as I would LOVE to have one, a split belt wouldn't really resolve that situation. It would dramatically decrease scheduling headaches for us though with all the performance ink getting ran these days around the wb product.
From experience, plastisol does in fact benefit from a longer, gentler cure. You see the difference in hand and washability.