I've bought Pixelmator, but every time I try to use it I find that it's just significantly different enough from Photoshop that I lose all my speed and efficien

I've bought Pixelmator, but every time I try to use it I find that it's just significantly different enough from Photoshop that I lose all my speed and efficiency, and just feel like I'm wasting time. I would really have preferred if it was just a straight subset of Photoshop's features, with the same key commands and paradigms, but more lightweight.