I use Blue Iris also and I'm very happy with it. Most of these cameras come with really bad software so something like Blue Iris picks up the quality of your camera system and it's worth every penny of the $50 it costs. I'm running a dozen cameras of different makes and models, from USB webcams to wireless IP cameras and Blue Iris handles them all. It's great to be able to buy the best camera you can get at the best price, configure it and then put it on Blue Iris to set all the masking, motion detection, emailing, etc and forget it.
The only real consideration in using Blue Iris is the power of the computer you run it on. Mine is idling right now with nothing being detected and recorded and I'm seeing 18% of my total clock cycles (processor power) being used by Blue Iris. That's on a six-core processor with 16 GB of RAM and three fairly decent video cards, it can jump to over 50% with several cameras recording.