At 16:34 05 July 2008, jcarlyle wrote:
My Zaon MRX alerted us to traffic at our altitude 5 miles
away, which then rapidly closed on us. Despite our best
efforts over the next 30 seconds, neither my friend nor
I saw anything approaching.
Then suddenly we saw a business jet in a 45-50 degree
bank less than a mile away. Apparently my transponder
caused a TA on his TCAS, he looked outside and saw our
wings flashing, and he turned away from the impending collision.

Assuming that you are talking nautical miles. If you are alerted
to the aircraft at 5 miles and within 30 seconds he is at 1 mile
then is apparently doing 480 knots (well above the 250 kt limit
below 10,000 msl).
If you don't see him and you know he is at your altitude and
closing at that high of a rate, why not just pull full spoilers and
dive to vacate that altitude as quickly as possible?
Is there a better option available?