Impact of using snapshot isolation and READ_COMMITTED_SNAPSHOT - will tempdb grow significantly larger?

Is one consequence of using READ_COMMITTED_SNAPSHOT

 that the size of the temp db will grow much larger, since sql will keep transaction details in tempdb ?

http://msdn.microsoft.com/en-us/library/tcbchxcb(v=vs.110).aspx

I think by default, sql uses pessimistic locking, which can lead to blocking
http://www.brentozar.com/archive/2013/01/implementing-snapshot-or-read-committed-snapshot-isolation-in-sql-server-a-guide/

I want to turn on this setting, but want to know all the possible consequences.

What other things could be impacted?