As you wish. But HD Sentinel does more for me than just inform me when my recording drive is getting low in space. It will tell me if a hard drive is less than 100% healthy, and allows me to check all drives periodically to see how they are going. This is important to me as the HTPC drives are now five years old, and could be starting to have issues, particularly the Recording drive which is constantly used, while the others are mostly worked much less.
I have a 3TB recording drive and I am still considering a 10TB drive so that I can leave a longer time between cleanup maintenance events.
Anyway, I guess this is a feature request then. I'll leave that to JRiver.
Failing having this feature, and knowing that objects can be placed on the Theatre View background via skin edits, I'm wondering if a simple Free vs Total space object could be placed into Theatre View for the drives selected for TV recordings. Just something like ;
"450GB of 3000Gb Free"
You could probably do that yourself using just Windows tools and components.
Maybe even format it to change colour to red if there is less than 10% free space, something like the bar chart HD Sentinel presents. See image.