I've actually been slowly figuring this out myself. After playing both DRG and NIN, MCH's play style is so different I've had to unlearn bad habits. For example, ninjas lose their combo if they do something like refresh mutilate, so you HAVE to finish a combo off or you lose DPS. Combos are also very specific so depending on timing, you can lose extra dps from having to reapply DE or SF. With MCH, it's much less about comboing and more about prioritizing. The 20 extra potency from Reload/QR doesn't really give you a lot, but if I've got Clean Shot ready and Reassmeble is up, I might pop it and Reassemble for the extra damage gain. There's much more situational awareness when it comes to abilities. Unfortunately, this can keep your eyes off the battlefield at times, especially if reload is cooling down, waiting for slug to proc.

I'm 37 now and I do feel a bit gimped without my turret. Hoping that changes when I hit 40.