Can I use my monitor speakers as PA speakers and will they work as well and if they won't work as well how much loss of performance will I have?

Can I use my monitor speakers as PA speakers and will they work as well and if they won't work as well how much loss of performance will I have?
If you are suggesting using home audio equipment professionally, I would highly advise against it. Home audio equipment is usually of inferior quality when it comes to the volume and power levels required to amplify in an normal sized venue.

The loss of performance will be quite noticeable at high volume between two $400 setups, one a PA system and one a home audio system.