Hello all, newbie here. I am interested in the 6400 and have seen the specs on the Flex website. I see that there was a previous model, the 6500, that was apparently discontinued. I guess I am confused about why a newer model has a lower number designation, and what the difference in features are. I have found a spec sheet on the 6500 but it is hard to compare the two models because the different spec sheets list different specs and there is no place where they are compared side-by-side. I see where they are offering a refurbished 6500 for $1000 more than the 6400. Is this a pretty good deal or is there something about the 6500 that makes it obsolete or soon to be obsolete?