The other plant I think that you are asking about is Hygrophila sp. "Brown." This hybrid can grow very quickly in a high-tech set up, and like grandulosa it is a bit brittle, so planting needs to be done in the same vein...with a little caution.
It does tend to creep, preferring to throw down aerial roots and spread that way. It will form side shoots quickly. The plant never tends to gain much in height, though, unless you trim the aerial roots, and even then it still tends to "leaning" at best. Interesting plant, for sure!
My understanding is that this plant grows alright in low-tech setups as well.