I've always said there is ZERO benefit in applying any sort of post recording processing if the analog gear you're using isn't absolutely top notch.
 
If I had a rack of 1173's, Pultecs, LA2A's etc then sure, go for it.
 
But I don't, and the little hardware I do own will be smoked by many/most of the bundled plugs that come with Sonar, so why compromise your recording?

Sidroe
Before I started using the Roland Studio Captures, I always had a dbx compressor inserted into the channel on my mixer to catch those peaks before they even went in to Sonar. With the Studio Captures, 12 of the channels have compressors built in the interface. I no longer even use the mixer! This sounds like a commercial for Roland! YIKES!

I have the Studio Capture also. I was under the impression the built-in channel compressors are after the preamps in the signal chain.
So couldn't peaks still clip on the inputs?