I have the META 357T V2 fitted to all my bikes and never had a problem, after 10 days they go into sleep mode and do not drain anything from the battery. I fitted all three myself and any I come across that were giving trouble was always due to poor fitting and poor quality connectors, even ones supposedly fitted by experts. Whereas all the CAT 1 types are good, the easiest one to live with is the META. I did a lot of research prior to purchasing my first meta 8 years ago. For peace of mind fit one and if you do fit it yourself take your time fitting it and route the wires cleanly, soldering joints and making full use of Heat Shrink tubing where ever possible. The oldest one I have which was fitted in 2004 and is still in everday use. I have never had anyone come back to me with problems from any of the ones I have fitted other than batteries for the remote controls.
However do not depend on the alarm alone, it is only a noisy deterent. Nothing will stop a determined thief, the idea is to move them on to an easier target.