FireDAC Change Notifications

[Larry Hengen 39]

I was looking at the MS SQL sample project demonstrating FireDAC support for change notifications.  Has anyone used this to refresh data-aware lookup combo boxes?

 

What is the real world database overhead?  How does it compare to polling?

 

The sample project works fine, but I've noticed that if you launch multiple instances with a unique subscription name, only one gets notified of a change made in SSMS.  Any idea why? 

 

I was hoping to use the sample app as a POC to help determine SQL Server overhead, and prove that all connected applications will receive change notifications.  I am using Berlin 10.2 and the only bug reports seem to be for Rio.