Pretty much. As I've understood it, if you have entered the Tarant Sewers before patching, and then enter them after patching, the game will crash because those sectors were changed. The same could apply to other areas and data as well. I guess that if you never go back to previous areas you'll be safe, but that's just an educated guess. If that's the case though, you could patch right before you enter Spoiler the Void since there's no returning from there. And if that breaks the game, you could just keep the saved game and reinstall and repatch to 1074.
The unofficial patch makes enough game changes where you're probably better off starting over anyway, frankly. Also, it does warn you that your saves won't work, so you really can't say you weren't warned if you try it.
