I agree that most of the 44cc and 49cc saws that followed the 49/52 were undoubtedly a huge letdown. The two exceptions would be the two Partner based models, the 490 and 590. They are well built and good runners. The rest of those small saws are kind of lame. I have a 450 and 455, which are almost the same thing. They are light and have good power for 44cc, but they just have a cheap kind of feel about them. I suppose that an indication of how much of a mess this all was is the number of models that came out in a relatively short time: 510/520/450/455/525/535. There was only so much that could be done with that chassis, and they brought in the Partners to try and turn things around.
We Jonny fans sometimes sound as if we feel that Elux/Husky came along and gobbled them up and ruined the purity of Jonsered. The reality is that if those small saws were an indication of things to come from Jonsered, then Elux saved their behinds and brought them back from the brink of going under. The 630 and 670 were decent replacements for the 621 and 70E, but what would have been Jonsered's replacement if they were still an independent company? Would they have been designed by the same folks that did the small saws?