I also played around with my DA sander.. the compressor struggles to maintain a decent operating pressure of 90 PSI. Despite this, I think it will still suffice for me. As a DIY'er needing to take a break every now and then isn't tooooo bad. It's also a trade off I am happy to make against having to splurge on a bigger unit, and also have the storage headache associated with the bigger unit.
It takes a big compressor to keep up with a da sander, I've a 14cfm compressor & it struggles to keep up with one. As you say, when you run out of air its usually time for a break anyway! Get you dusk mask off & let the feeling come back into your hands!
A good quality sander is a lot more efficient & wastes less air. I noticed this going from a parkside to a dynabrade sander.
Invest in good quality sanding discs, they will sand better & outlast cheap ones many times over. Dust extraction is essential, otherwise the disc clogs up very quickly!