Expandables are only able to survive on the market because of the tons of people who are unknowingly shooting an untuned bow. Guys at the archery shop will tell you if you shoot over 260 fps you canot get fixed blades to fly straight. Let me translate that for you - When the bow shoots that fast those guys are unable to tune it properly, it gets finicky at that speed, and most pro shop guys are not good enough to do it right or don't want to take the time. Not to mention the fact they make more profit on the latest expandable on their shelf!!
I agree with the inability to properly tune a bow at a lot of proshops, that's why it's best that one learns to do things for themselves.
Other than that, I wholeheartedly concur with Rack. I can tune a bow and shoot both with great success. I choose to shoot a larger cut quality mechanical as I'd rather "waste" my extra ke cutting a bigger hole than burying futher into the ground on the exit side.