360 shmup region lockout ?

If I am not mistaken, Shikigami no Shiro 3 and Raiden Fighters are all region locked for Japan only. Are there any other 360 shmups besides Ikagura and Trigger Heart that will work on a US 360 that are worth checking out ?

Yes, Shiki 3 and RFA are both region locked, but it's possible that they'll both get a US release eventually. So far, there haven't been any other retail-released shmups for the 360. Ketsui, DDP DOJ BL, and Otomedius are definitely coming out, but it's 99% likely that they'll be region locked as well. If you consider it a shmup, you could get the US version of Senko no Ronde (it's pretty cheap these days).