I have both the geil is good if you have a cpu that will run 280fsb+ I've ran my geil @ 295fsb 1:1. it is good for lower multi chips 2.4 2.6. Slack timings though so you need high FSB to make up for it.
Mushkin is good for 2.8 3.0 3.2 chips Tight timings 2-2-2-6, but then running 5:4 a high fsb will give you the same as the geil. Depends if you are on a 865 or 875 and can get pat to work @ 5:4.
There's a lot more to it. But if you can afford the mushkin get it.
But they are out of BH-5 at mushkin.com so if you can find it snag it up fast anywhere else.