How large are the databases on which maintenance is being performed? Terabytes??

Are you using Maintenance Plans or custom scripts? In my experience, custom scripts (especially Ola's) are more efficient. Perhaps you are using the sort in tempdb option on the index rebuild?

Personally, I like to separate the I/O and run tempdb on a separate LUN. However, if the disks are slower than the current configuration, then I'm not sure you will see much of a performance boost.

Without a doubt, you will see a boost by moving anything to SSD.