You might review, for example, the last three years of 407 accidents and incidents, and redo your analysis to determine what the current statistics say, now that the 407 is mature, as opposed to its introduction as a new product. I took a quick look of reports in the NTSB data base since 2005, and saw 22 reports. While there were engine failures, you didn't see the type of events experienced early in the 407's history.
One can also make the argument, that in a perfect world, the only accidents would be mechanical problems, with pilot training reducing the human error accidents to almost zero. Since you have trained at Bell, you know how great their 407 training is.
I don't think comparing the 480 to the 407 is an apples to apples comparison, when you look at the number of 407s in the fleet and the number of hours flown by the 407 each year. Wouldn't the 407 fleet fly 100 times the annual hours flown by the 480 fleet?
In the last ten days, I flew a 407 from CO to AK, and a L4 from AK to CO. Two and a half days up in the 407, and four days down in the L4. Along the way, I stopped in Penticton and did two days of mountain training in the 407 with Canadian Helicopters. Previously I have made that trip from the lower 48 to Alaska, and also trained with Canadian Helicopters in the Jet Ranger, L4, and 530F. The 407 runs circles around all those other ships both in the mountain environment as well as on a long cross country flight.
While there are always opportunities for pilots to screw things up, the 407 makes the flying part a lot easier between its great power, the responsiveness of the rotor system, the tail rotor authority, and the ability to do slopes. Several months ago in the 407, we needed to climb high to cross a high mountain pass in Colorado with a bunch of wind and turbulence, and easily climbed to 15,500 feet where we were still climbing 700 fpm. If you mated an L4 with a high altitude tail rotor with a 530F, took their best attributes, and added in a bunch of attributes neither ship has, you end up with a 407.