John, you're right that modifying the board that way gives an extra rear rank board location for each side to place a third bishop, and, being 3 pentagons per hexagon, this also gives a 45 position board, fitting the contest theme. I have 2 objections to that, however, The first is aesthetic. The board will be a parallelogram, with corner angles of 60 and 120. It doesn't look right, and it's annoying to play at an angle like that - you want to grab the board [right off the screen] and straighten it out. The second objection is concerned with playability.
Take a look at both of the boards. The center row of one is 3 hexes - 9 pentagons - across. The other is 4 hexes, and 12 playable spots in the middle of the board. The 3 extra spots in the center on Graeme's board are the one that was lost going from 46 to 45, and the two that the extra elephants occupy, now in the back rows. Does this make much of a difference?
How many pawns does it take to make a solid wall completely across the board? In Graeme's game, in the setup, the 6 pawns cover the 3 hex board 'row' they're on, occupying 2 of the 3 pentagons in each hexagon. To do the same in the middle of Graeme's, you'd need 8 pawns, which the game doesn't have. The middle of Graeme's board cannot be clogged by pawns. On the 45 position board, it only takes 5 pawns to clog [form an unbroken line from side to side] the board. There are 6 pawns in the game.
In general, especially with all other things being equal, I believe that the narrower the front, the easier it is to jam it up with pieces and kill zones, so the more drawish it will be. Further, Graeme's board is very roughly circular [at least in intent], giving maximum room for maneuver in the center of the board. This game won the contest because it 'plays big'. It feels like the 64 square game, even though it's on a much smaller board. It also doesn't feel crowded, thought the starting piece density is ~60%. Narrowing the board from Graeme's 6-8 pentagons down to 5 pentagons, losing one spot and adding two pieces would likely create a clog in the middle of the board, in my opinion.