Lock and MRX (not XRX)
One RV7A report:
Lock: I do not have a lock for canopy. Never had any mischief. Put my trust in 18 USC 32, making it a federal crime to damage, disable, or destroy a plane. (Definitely would report to law enforcement if I had any molestation, and like to see those warning signs posted at airports.) I follow minimal best practices: record avionics serial numbers and keep a canopy cover in place if you leave airplane overnight or at unattended airport.
MRX: Mine is installed in the panel, using factory panel mount fixture, very similar to Dick's, though I located it low and to right of center of pilot instrumentation. I actually think the MRX worked better when used as a portable, simply on a velcro dot on top of the glareshield. In the installed mode, my MRX seems to pick up ghost targets at surface level when I am at/below 1,200 feet. E.g., when in traffic pattern, it reports "traffic" at -800 or -1000 below me, which I simply disregard. Seldom at my current rural airport home base where there is no radar signal whatsoever below 3,000 AGL, but still happens so I think it is ground signals (radar detectors? microwaves? confusing comm radio or VOR signals?). More often in moderate or highly populated areas airport areas. All other functions seem reliable.
That said, I really like having the MRX for basic "alerter" function when enroute/arrivals, and looking forward to a "some day" upgrade to ADS-B/FIS-B information. But, since I had no performance improvement, and this one low altitude problem, from installing it in the panel, I would not do a permanent installation again.