I think in the upcoming match West Ham has a chance to get three points. Moyes' team has an excellent form, plays at home and has no serious problems with the squad. Brighton is a strong and played team, but recently the Seagulls have often lost points. Although in the last round Brighton managed to inflict a defeat on Tottenham. So West Ham is waiting for a tough game.
I think Brighton also have some good players. Hammers on other hand are also a tough team. I think both are on equal terms. If we take performance into consideration then obviously West Ham are performing better but make no mistake of undermining Brighton at all because they had crazy last season and are capable of big things for example the last game win against Spurs with 4-2 scoreline. Its hard to pick a winner but I expect both teams to score in this match.
Usually when they appear at home then it will be better and confident in the game, for example Brighton when at home was able to win 4-2 with Tottenham and so when playing in front of their own fans have a different atmosphere.
You said right, West Ham and Brighton are almost equal in the game and the statistics are not much different, if you look at the results now especially playing at home then West Ham will be more favorite even though the odds are not much different, I can only guess where West Ham will win, but if Brighton wins I will not be surprised because they can play even crazier.