I must agree with Uncle Dave. You'll like the stereo system better. And I looked at that new Peavey system last week. It is powerful, light-weight and portable. Seems to be ideal for your needs.
One other thought--if your church has an existing p.a. system, it may well be possible for you to plug your keyboard into it. When I use my keyboard at home, if I need more than the onboard speakers, I sometimes plug it into the auxiliary input in my home stereo system. You must be careful not to turn the keyboard up too load or it can overdrive the home system, but it sounds great.
Don