Yes, some swords can grow gigantic (like this Veronica / Red Diamond sword).
http://www.forum.simplydiscus.com/sh...ad.php?t=54708
Some of the hybrid swords usually stay smaller, but not always. Echinodorus Kleiner Bar stays medium sized most of the time. Usually Veronica stays medium sized too.
Avoid the Rubin sword and the Ruffled sword (Echinorous martii); they both can grow huge.
Of course, you could always stick with the pygmy chain swords.
Walter