Both have the possibility of dangerous side effects: including complacency, the rejection of the call to repentance (or denying this call to others), and the possibility of the hardening of the heart to the degree where personal versions of the doctrine deny justice and mercy.
Whereas God calls men everywhere to repent and believe the Gospel, Calvinism tells people that unless they were specifically selected (and it is impossible to know for sure who is selected and who is not) that it is impossible to repent, and any attempt to repent will be rejected. But from the opposite angle, if you are among that secret elect, you need not ever attempt to change your heart to repent, for you shall be saved no matter what you do or whom you will to serve.
In this regard, Universalism is similar to Calvinism; it only says that everyone that ever lived and ever will live is among that secret elect. However, Universalism does recognize some measure of hope and some limitation upon infinite cruelty. Calvinism is not necessary bound by the doctrine of infinite torment: I am aware of some Calvinists that do believe that God will literally destroy the wicked, rather than grant them eternal life in torment.