It would take us faster, and I would have to leave them alone because unless I have maya, they're going untouched. The reason I am opposed is because the assets he proposes look like something out of counter strike 1.6 or a ps2 skating game, and my concept is of a game with a striking palette and a very brushwork-y style.
I would also be limited to the 10-odd city buildings the pack has. If I wanted a specific kind or shape of building, I would have to suck it up and choose one from the list. It was also already established that I was in charge of the game's visual direction. He is only the programmer. The idea was that he would make an engine for me and we would work together to make it accomplish able but still fun, and I would fill in the content like items, monsters, game areas, quests, art etc.