Not trying to downplay a cost effective alternative to a weaponlight (or should I say dedicated weaponlight - a flashlight that has been specifically designed for a weapons platform, such as a forearm light for a specific firearm or a light designed for attachment to a rail on a firearm). I am simply not a fan of rigging gear to work when I can purchase something designed for the job. I've been through enough 100mph tape and 550 cord to know that rigged items can and do work. The description of the flashlight you've described (as upgraded) sounds like it's up to the task.
I understand how hard it can be to justify a dedicated weaponlight's cost when it's not part of your job or doesn't mean the difference between life and death. I am no physicist and cannot explain the difference between the physical shock sustained by a weaponlight dropped out of a C130 and the shock produced by a firearm.
What I do know is there are some very creative, cost effective solutions to having a light mounted on your firearm (many of them listed in this forum). Personally the M500 series seems to do it for me since I have no need for rails and I don't like a vertical foregrip. I've also had issues with taped/velcroed pressure pads as well as flashlights in 1" rings rigged for an AR platform (on one rig I saw, the owner said "all you have to do is to turn the tailcap just right so when you tap the tail end with your index finger, the light stays on" . . . not my choice for reliability).
Since I don't have the money or resources to conduct the testing and research that weaponlight companies have conducted, I've taken the word of other shooters that have utilized dedicated weaponlights to make my decision. Otherwise, I'll have to trust Surefire's engineers as to what's been designed for attachment for weapons or not.
I do like to hear about homemade rigs that work (which is why I hang out around here), and I'm more than happy to know that your system has sustained 1000s of rounds while mounted with no adverse affects.
I suppose what I'm trying to say is that my previous post was simply my opinion on what I would do if I had a rigged light system attached to my personal firearm. YMMV.