grenv: *nod* i looked at the dice
3&6 bear off with: 3+3,6 & 4+4,6 & 5+5,6 & 6+3,4,5,6
4&5 bear off with: 3+3 & 4+4,5,6 & 5+4,5,6 & 6+4,5,6
both have 10 rolls to bear off (out of 36 possible rolls)
but! there might be a difference with the left over in case one isnt able to bear off .. for example one rolls 1+2 .. then the position 3&6 will bear off the 3 piece leaving a single 6 piece .. where the 4&5 position cant bear any pieces off leaving 2 pieces on the board closer to the finish
so 3&6 might be better in case one doesnt bear off at the first roll ... but i am not sure about this one