I not only have all my computers connected to the Internet, I don't run any anti-virus software. And I use a cloud service for backup.

I do have a firewall.  I also use WinPatrol, and I don't use IE or Outlook.  I've been on the net now for two decades, and haven't had a problem.  You just have to be reasonably careful.  

It's not being connected to the net that's making me hesitate.  (You don't have to be connected to the net to use Adobe cloud software, BTW - at least, not all the time.)  It's what's going to happen when the year is up.  Will they jack up the price, and if so, will I find it hard to go back to my old version of Photoshop?

I'm also not sure I want to encourage this software rental thing, by giving them money for it.  Even if it's less than I would have paid to buy Photoshop.