[punter11235]

The equity is higher on 2 3 board because :
a)you took 2 cards out of the deck so probability of 3 following hitting your hands is higher than with 48card deck (here you are dealing 3 more cards from 46 instead of 48 , you removed 2 "useless" cards from the deck)
b)sometimes 23456 straight tie the board.

a) is more important by a lot;