I've been running System Mechanic (basic) and 360 together for a couple of years. I have the System Mechanic auto scans and the system protection module turned off. I haven't had any compatability issues that I'm aware of. The System Mechanic registry tool did remove some Symatec keys that were needed for 360 Help to work. Since then I've not let the System Mechanic registry cleaner make recommended registry changes. It also doesn't recognize the firewall in 360; so, you'll get an alert until you suppress it.

I probably won't renew my System Mechanic license when it comes due.