There were a few thoughts behind the choice. I had the lunchbox thicknesser and the 6" axi planer when I got a good deal on a used Inca planer thicknesser, with tersa blades. Brilliant machine. It only does 9" though, and there is a slight chance of needing something a bit wider. So I kept the lunchbox thicknesser for that and sold the planer to create floor space. In actual fact, I never got around to selling it, and it fits under my bench, so no big user of floor space.
The other advantage is that if I remove the worst of the high spots by hand, I can get away without the planer and send it straight through the thicknesser. The lunchbox thicknesser can be lugged outside where I have plenty of space and no need to worry about dust extraction.
Finally, one day I may replace the head with a helical one. I think that Byrd do one that will fit. possibly a pipe dream, but if I sell the machine, I won't get much money back.
The Inca would do most of what I need, almost all. The thicknesser does such a good job that for what it owes me I am happy to keep both.