I would say the Illusion should be a little bit weaker compared to the Kinetic.  It's also a higher RG (2.53) than the Kinetic (2.48).  If I had to choose b/t the 2, I'd probably go with Illusion for 2 reasons:

1.  It's designed for medium conditions (which was what the Equation was designed for) which the Kinetic I believe is designed for medium-heavy.
2.  It's highly versatile.

If you're into the Track line though I'd also take a look at the Temper.

Here are links to info on all 3 balls:

http://rotogrip.com/products/balls/ball.asp?ballid=69
http://trackbowling.com/products/kinetic.php
http://trackbowling.com/products/temper.php

Hope this helps.