From personal experience I would recommend a good firm board… a place where I used to work, did not like to provide quality cake boards (to save expense). Flexing of the cake, when it was moved, caused problems with the strings becoming loose and crooked. Time spent trying to fix it… could have been avoided by spending a couple of extra dollars in the first place!
Julez, https://www.facebook.com/pages/Allways-Cakes/450634018350115?ref=hl