Hello Robinson,

comparing tuner sensitivity between SF4008 and HD51 is still outstanding - i will do it when the weather will be warmer. I do not know about VU+ tuner sensitivity.
What other DXers report is that the SF4008 has a pretty sensitive tuner.
In the HD51 i have a single tuner and it reports itsself as a Si2166D (i do not know if a HD51 tuner slot supports a twin tuner as well).