[Elecraft] [KX3] Changes to newer models?

[rick jones]

I'm considering purchasing an older KX3 S/N<16xx. From anything I can determine the encoder was improved and there was a slight change to the 160 and 80 meter filtering. Oh and the heat sink. Is that it? It appears that there have been circuit board revs but I can't find any information on what they were. Just wondering if those revs substantially improved performance in any way.  Thanks. Rick