I don't think that there are any big differences in GoT, so feel free to go for the cheaper version.
Actually, I'm not really a huge shmup fan. The other games on your list are either over priced (i.e. - Exile: Wicked Phenomenon, Lady Sword, and Sapphire), not universally enjoyed and therefor hard to recommend even though I like 'em (i.e. - Loom, Shapeshifter, Camp California, and Order of the Griffon), mediocre, or I haven't played 'em enough to recommend them.