10 knots is the max tailwind limit in every Part 25 aircraft I've ever flown - except for the Dash 8 which could go to 20 knots under certain conditions. Circling sucks in a jet, period. I would not circle unless I absolutley had to and then I would seriously consider wether or not I wanted to land there. Even in a straight wing Citation the circling speeds can easily be 125 to 130 knots. Circling at circling MDA's in a Cessna 172 going 70 knots is one thing - doing it in a swept wing jet doing 140 knots borders on dangerous......why do you think the majority of airlines aren't allowed to circle?? At all of the airlines I've flown for require the weather to be 1000 & 3 before we could circle. My CRJ type says "Circling manuevers in VMC only" or something to that effect.
I won't go so far as to say that all circling approachs in jets are dangerous BUT when we're talking about a 180 degree circling manuever, especially at night(which I know this wasn't), you really have to start thinking about what the safest course of action is.
Just out of curiosty - did this airport have weather reporting or was it an 'estimate' of 5 to 6 miles visibility based on landmarks around the airport that locals would be familiar with?? Where was the sun?? Just because departing traffic has 5 to 6 miles in haze doesn't mean that opposite direction traffic had 5 to 6 miles viz. Yes, the Citation crew could probably have done more things to make their presence known but you don't be too quick to judge - you don't know what was happening in the other cockpit. I've been around the block a few times and for every time I've 'dorked things up' at an uncontrolled airport in a jet, I can tell you at least one story of a GA pilot dorking things up.
Not triing to start a war - just food for thougt.
Jason