if both photographers are of equal skill
I'd go digital
why? simple, flexibility,
the guy can take hundres of picture and or delete crap ones as he goes along.
as long as hes backing up etc he shouldn't loose any data
and (HERES A BIG ADVANTAGE)you can check the group pictures there on the day if he has a laptop with him and redo them if you think they look a bit crap or someone has thier eyes shut.
the 35mm guy even if he gets good shots still has the risk of mis-developing the film, maybe the camera not winding on properly etc etc
I'd also put a couple of disposable 35mm cameras on each table for the guests to play with and just collect them at the end and get them developed.