I love dealing with independent providers, but I will say scheduling is often easier and more reliable with an agency.

Interesting observation and thanks for starting the discussion. Before I respond, I put the disclaimer to my response that this is a really broad topic and agencies vary as do independent providers.  With that being said, I would respectfully disagree.  I have used both and have had more late shows and cancellations with agencies than independents.  I would agree there is more variation with independents (as to be expected), but if you are careful with who you see, independents are just as reliable as most agencies.

I guess it just depends

My dealings with Indy's is a high percentage pain in the ass.  I have to caveat that comment because I know there are plenty of Indy’s on this Board that are about business.    Even being certified with double digit OK'S on two major provider sites have left me frustrated. Even through this Board I have had no response to emails even to current ads on the Board more times than not.  I use one local Agency that has never disappointed  and will continue.    
Second point, I really don't want to continue to give out my personal information to every Indy.  I know everyone's experiences differ, this is just my take