The ArcSys employee I mentioned above made a new thread for questions and feedback regarding +R.
Some highlights so far:
ArcSys have created a small team to handle matters regarding PC/Steam
"Our team's goal is to be able to bring the latest games onto Steam [...] There's quite the backlog there, but we'll get there eventually!"
"More titles are definitely underway, but most are still pretty much tentative in nature."
The success of previous ArcSys titles on Steam was the driving force behind the decision to port +R and a potential PC campaign
ArcSys are now aware of the freezing issue w/ certain stages in +R, and Shini will be "checking with the team" to see if it can/will be resolved