I am planning to move to open source FEA softwares. I found out that CALCULIX is one very good software with almost all the capabilities. Though I don't know about the accuracy of it. Can anyone compare its accuracy with ANSYS or other good FEA packages? And are there any demerits or flaws in CALCULIX? (Recently I came to know that one can only use linear elements at the slave surface while defining MPC contacts)