The University of Illinois today posted on their FarmDoc Daily analysis on the final harvest price for corn and soybeans. The spring projected price for corn was $4.62 and the final harvest price was $3.49 which is about 24% lower. This means if you elected 85% RP crop insurance coverage, you will have a crop insurance payment even with up to a 13% increase in yield. For example, if you APH is 160 bushels, you will collect a crop insurance payment if your final yield is 181 bushels or less (160 * 1.13). Above 181 bushels, you will collect nothing.
Soybean spring projected price was $11.36 while the final harvest price was $9.65 which is 85% of the projected price. This results in a factor of 1:1 for 85% soybean RP crop insurance. In order to receive any soybean payment, you will need a yield loss.
The post has a very nice table letting you know the amount of yield gain you can have for corn and still collect a payment. The bottom line is if your coverage level is 75% or higher, you may still collect a payment even with a yield gain for the year over your APH.