I've yet to grow the C. crispatula v. balansae but the C. retrospiralis will get very tall. I have had that grow across the top of my 75g. Same with C. spiralis. Either the spiralis or retrospiralis can be pruned back by either trimming the taller leaves (they will melt) or removing the leaves where they exit the substrate. I prefer the first, but I am lazy
I do believe C. retrospiralis and C. crispatula v. balansae are different plants. They appear to have different width on the leaves with the retrospiralis staying more narrow. Again, I have not had the opportunity to grow the balansae to compare the two.