Well, if you do not care for that Security Advisory on your machine,
it will be worth carefull testing.

On a single HT-cpu machine I found (for my server applications) the overhead
of the SMP kernel to eat almost exactly the additional performance the
HT parallelization offered. So there was almost no overall performance
difference between a uniprocessor kernel (no HT) and a SMP kernel with HT
enabled in the BIOS.

This was for *my* workload, and over a year ago. I disabled HT on that machine.

Newer CPUs will offer higher parallelization, and your workload will differ.

I have never seen lockups or crashes while running SMP/HT kernels.

Martin