The fact That The beetle is 170% effective Vs Xan Fi, means that yes cath co can roid Xan Fi.
http://beta.planetarion.com/bcalc.pl?id=1htgql4zjy4131u
As for Cat Cr They cant Roid Xan Fr solo but they would be able to roid any xan Fi/co Planet because of the value they would have in anti cr/bs.
Cath will Still be a Very strong early and mid round fleet, and if they keep there value and actually hold there roids long enough they will be VERY hard to roid solo.