I love how people always use the "Pendolinos are so safe" arguments. They have been in one accident, and in general terms it wasn't that bad. The ATP was never in a single crash, so how can we know how it would perform? Remember, up until very recently the Mk3 was regarded as ultra safe, now all of a sudden it's this awful deathtrap that will disintegrate in even the most minor accidents. Remember that until Clapham nobody had second thoughts about the Mk1's safety, in fact they were a big improvement on what went before. Mk3s have survived high speed derailments like that at Grayrigg. Ever heard of Colwich, two trains colliding with a closing speed of around 100mph and only one person killed (the driver). The trains were formed of Mk1, Mk2 and Mk3 coaches.
To be honest, a bigger factor in the survivability of Greyrigg compared to other similar accidents was probably not the structural strength of the train, but the interior design, reducing injuries from people flying around in the derail carriages. The small windows might have played a roll too, reducing the chance of ejection, but I'd much rarther have big windows and take the risk given the highly unlikely chance of being in an accident where I might get ejected from the train. Trains are very safe. If you commuted to work every day on Mk1 EMUs you were more likely to be killed crossing the road outside the station than on the train. Don't worry about it and just relax and enjoy the ride, whatever type of train it is. The chances are not a single member of this site will ever be involved in any kind of rail accident, let alone a serious one.