I never could understand people complaining of desyncing errors.  I've had a few early in Diplomacy development, but I haven't had any in over 2 years.

I've been running the same game for the 3-4 weeks, playing on the weekends (multiple players: one local, other online).  I always use direct connect and never ICO.  Granted, I am playing through an early, minimal version of my mod (switching to my full once this game is up), but I still have a good 2 hours left to finish up the enemies.  My only problem is traditional late game lag, but it's been tolerable.

I've never had connection issues with direct connect either.  Most of the issues seem to be ICO related; all the more reason for me to never go on there.