It all depends on what you consider a 'false' alarm.
Stationery locations of door openers of x band and k band are bonafide sources of radar even if not police radar. Technically they are not falses.
Emissions from cheap radar detectors often on the frequency band of the very wide ka band are more the sources of falses.
If your primary interest is in having a detector quiet to the first type mentioned then either the 9500i or 9500ix can provide the ability to permanently lock out (by gps coords) such sources. The 9500ix can also be configured to do this automatically. But be aware that this approach is not fullproof. In some instances users have reported real police radar being locked out!
If you are more concerned about the latter, then either the 8500 x50 or rx65 should prove just fine.