If you are close to a payout then by all means switch off the Adprogram to get the payout. You can always go back to the Adprogram later.
Your understanding is right. When you have the Adprogram on you only have one direct adsense ad at the very bottom of the page on the right. How many people are likely to scroll past all the other ads that are in your face and click on the very last ad? Not may.
Putting just adsense on will mean you will be relying on clicks to make income and no longer making money solely from views. It might be a good time for you to test and see if Google Adsense performs better for you than Adprogram.
If you want more details then check out the lens I wrote about the new layout http://hubpages.com/community/is-the-new-hubpages-...