I also use a MiniPC running pfSense and couldn't be happier. I made the switch 3 years ago, after running a Linksys WRT54G-TM on OpenWRT for 5+ years.
pfSense is simple to get started with, powerful enough for small to medium businesses and "just works."
The initial setup might be a bit more $$$ ($150 for hardware), but it will last you a long time.