That sucks they'll balance the game for 4 parties companion. Baldur's Gate 1 and 2 looks +- well balanced (in général) and you can play with the companion numbers you like, from 0 to 5.
Of course the difficulty increase if your party is smaller, and that's what gives a taste for replayability. In other crpg they usually have to cheat and create "Lone Wolf" skills because everything need to be over balanced... every new game is the same, with the exact same difficulty everywhere.
