<p>For this WCF service I have developed, I have to set MaxReceivedMessageSize to 5MB. My current problem is figuring out whether it is better to have a larger MaxBufferPoolSize value, like 5MB, or retain the original 512KB value.</p>

<p>Does anyone knows what is the recommended setting for this scenario?<br>
In short, should I set MaxBufferPoolSize = 5242880 (5MB), or MaxBufferPoolSize = 524288 (512KB)?</p>

<p><strong>UPDATE:</strong> For clarification, the service is meant to insert a new customer record along with some scanned documents. As a result, the message size may reached up to 5MB.  </p>

<p>We <em>could</em> try and separate the upload of the scanned document using alternate technologies, but the requirement was both customer record and scanned documents must be in the same transaction, so we decided to go with this approach, until we figure out how to use WCF's transaction capability.</p>

5 Mb seems like a lot of data to transfer over a Web Service.
The first thing you should look for is to send less data.
Secondly you need to set the size to your needs.