I use PFSense and Snort at home and it's perfectly fine for the price I paid for it, but enterprise grade it ain't. I wouldn't use it to protect a network worth more than my beer budget.
I don't know what business you're in and maybe after a nightly tape backup there's nothing important for you to lose. Frankly that's most small businesses. But if you've got real trade secrets get a proper IDS/IPS before you regret it.