I spent HOURS picking shavings off of it before I would even think of installing it.
That's unfortunate, but just for added perspective, mine arrived perfect and I haven't heard any complaints from the multitude of members in my group who've bought one. I've had JC ports heads for me also, and they've been great as well.
You'll get faster revs out of your motor with a lightened flywheel, but the reason for me purchasing one was to help avoid shearing the woodruff key in my crank, which happens on motors that make power.