I e-mailed daVinci to inquire as to the max tire size the 700c rims would accept. Todd Shusterman replied the same day with the following:

"You will have plenty of room and rim capacity to run 32mm, 38mm, or even
bigger tires.

I run 120 to 125 psi with 28mm wide tires. That is higher than most tires
had listed as "Maximum", but the number tire manufacturer use is half of
what the blow-off pressure was. I have talked to two tire manufactures and
both were very comfortable with 120-130 psi. You would probably use a
little less pressure with 32mm, 105 to 115 should do the job nicely. I do
not have personal experience with 32's. You want to make sure you have
enough pressure to avoid pinch flats."
We'll try the 28mm tires initially. Our riding will be very tame for a few hundred miles in any event. It's reassuring to know I can put larger tires on the frame; definitely a good move on the part of daVinci and one that eases my concern about 700c wheels.