I think that the current case that you sell is doomed from a usability standpoint and a complete overhaul is needed to make it really usable. Take a look at dangerousprototypes.com/category/cases/ to see all the case designs so far.
I’ve just noticed that the best version is already available for sale at synthetos.com/ although I have no idea how big their stock is or whether they can actually provide the cases.
Maybe you could team up with the guy because it’d be nice to buy everything from Seeed and shipping prices would be much lower.