Tonias are nice plants, I initially did not really care for some species, they grew too fast or looked too much like Egerias.
The belem and manaus are nice varieties.
Most plants get used any no# of ways, but that's really what you can pull off nicely.
Gardening is something that you must like to do and be in the mood, set aside the time to do it.
But if you are willing, you can trim the heck out of many typical mid and background plants for the foreground.
But after a few years, you get tired of it
I suppose Amano is no different, he choses plants based on where they are best suited for labor and if you neglect trimming. It's fine to break that rule, however.
I doubt Amano would disagree either.
Regards,
Tom Barr