This was my first K-Meleon upgrade & I was a little apprehensive.
I have found that the auto-update isn't working for me, I have ticked both boxes but when I restart the browser the second box (Macro Extension) doesn't stay ticked. I may not have the macro.
Anyway, I manually downloaded 1.5.4 over 1.5.3 & it seems fine so far, all bookmarks & even my GB-English dictionary ('borrowed' from SeaMonkey) are fine. Apart from the fact that the Privacy Bar had returned to its defaults, although I can easily remedy that.
K-Meleon ~ Not a Melon!