Aside from the mystique of the pre 64 model 70, these new ones are every bit the equal of them, and also new, and not 50 plus years old.
The TRW mystique is further strengthened by the growing pains suffered by Winchester and Harrington & Richardson in 1960 and 1961. Overall, it is fair to say that TRW had the most trouble free production record of the four manufacturers. Sometimes it pays to be last but it always pays to plan well.
If a one piece op rod had been necessary then SA would have drafted the specs to require that. TRW made a large quantity of spare bolts but made little else in the way of spare parts. In my opinion, the mystique surrounding TRW rifles and parts is unwarranted.
The Colt "mystique" was totally debunked for us many decades ago, unfortunately. About the only thing that has come out of Hartford that I'd put my faith in was the SAA... and that's why I was quite happy to hear that CZ had taken over- with sincere hope that someone would finally fix what has been broken for far too long.
Where did TRW get the mystique? My older SAI (72***) has a TRW bolt, but that's the only TRW part I have had on a rifle ever, and I've owned some real shooters. I actually had never heard of the cult of TRW until I jumped in this forum a little over a year ago. Prior to that, in spec parts were in spec parts.
The TRW mystique comes from these facts; #1, When they got a contract to build the M14 rifle, their manufacturing techniques were considered ahead of the times and, they put together a special group exclusively to do, and oversee production & manufacturing.