I can't decide if I hate synthesis or am intrigued by it. I would kill for a DLC that takes place after the events of the synthesis ending, that features Shepard, but without the new DNA (its a fan fic/dlc wish I've been kicking around in my head).
One of the reasons synthesis bugs me is because, despite EDI saying that "We will remember," I think Shepard will be forgotten by everyone he helped to "up lift," including his LI. I'm basising my belief on a concept called, "The
Sentience Quotient." With everyone becoming a higher life form, almost devine like, how could they relate to any of the people that died before Synthesis? That would kinda be like anyone of us weeping for the Neanderthals that died so we could evolve. Synthesis would create this astronamical gap in the sentience quotient that would make any sort of rememberance, or interaction, meaningless. Basicly with everyone that came before, becoming an inferior life form, how and why would anyone, and could anyone "uplifted" possibly care or relate to anyone who came before? Even your LI.
Ofcourse, this is all just my opinion.