My trophy syncing problems are no more. After the initial problem not long after MW2 released (just usung that art a timeframe indicator not as a suggested cause) I've sync'd a number of times without any major issues (get the error once, then try syncing via a different route and no worries).
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix