I've seen and fitted many differrent units over the years, but the Traxide unit is by far the best and most versatile unit on the market that I've seen. It does heaps more than other do, and yes it does draw from the starting battery - but cuts out way before it will ever be an issue to start the vehicle.
What it does do is bring your starting battery to a much higher state of charge after a few weeks of use - before running one in my L322 I used to get intermittent faults when starting the vehicle - ABS and traction control stuff due to a dip in the battery volts when cranking. This was completely eliminated with the Traxide kit.
I'd suggest your Auto Ekectrician is just pushing the brand he sells onto you because if he really did know his stuff, he wouldn't make claims like that.
Oh, and I'm an Electrician with over 20 years experience on isolated power systems, so I actually understand what the Traxide kit actually does, and what others do (or don't do as the case may be).
My advice would be to find an Autolec who doesn't bag out gear he knows very little about - I just find that unprofessional.
Just my 2 cents, I have nothing to do with the Traxide product, just used and installed several of his variants into vehicles and found them to be far superior to other crud on the market most of which is just a voltage activated switch and has no smarts at all - often for a similar or higher price than the Traxide kits.
I would highly recommend them and it sounds like you can do your own stuff, installing one is a snap.

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