I'm going to be doing an indoor shoot in a couple months as a second camera. I have an XL1s a the other camera is a PD150. Are there any settings on either camera we should be aware of to help insure a seamless mix in post? Is it even an issue?

Check out this thread

http://www.dvinfo.net/conf/showthread.php?s=&threadid=9504

The PD150 will probably be a little sharper and less color saturated than the XL1s. White balance the two cameras together, then crank up the saturation and crank down the sharpness just a bit on the 150. You'll need a good monitor with an A-B switch to do this. Then you can do whatever additional color tweaking may be necessary when you edit.