Could not, even if I want, the 3 letter code is a standard for exchanges. I don't know where coinHunter came up with his 2 letter code idea, but would crash most of forex programs made to split currency pairs (EURUSD, AUDCAD, GBPYEN.... etc), if solidcoin ever make that far.
Well I can tell you what most people are using, by not using the standard you create the possibility to confuse. Either way it's just a small thing, perhaps forex will give SolidCoin an exemption?