Cremation seems far more like their style in making sure that the body and all evidence was no longer able to be found and also very probable given that the mob or members of the mob owned the crematorium. It could all be done in house without having to hack up the body and send it out to parts unknown. It's just too bad that sufficient DNA could not be obtained from the floor/boards in order to achieve a 100% documented proof that it was Hoffa's blood. As I said though, for me, there is enough circumstantial evidence to justify belief that this is how it happened and what happened.
The only surprise to me is that it went down like it did in that Hoffa wasn't killed in the car. Actually the way this went down, with the exception of how they got rid of the body, mirrors a scene in Goodfellows movie where the character in the movie, played by Joe Pesci (Tommy DeVito in the movie) is killed in a similar way as he enters an empty room of a house where he thinks he's going to become a "made" wise guy only to find out it's a retaliatory hit ordered account of his previous killing of another member of the mob that wasn't sanctioned.