I'm not real familiar with the PSE line, but I do know they make a good bow. As for why your shots are opening up, it's because you are getting tired. When you start to feel tired, set the bow down or you may develope bad habits that will be hard to break. The more time you spend shooting the bow, the longer you will be able to shoot without getting tire.
Oh yeah,

to the forum!
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That look on my face is not concern, its shock at your utter stupidity!
Check out Redneckarcher.com. It's an adult archer/hunting site that feels like hunt camp.