Routing Joystick mount plate area question

[GAtekwriter]

I've decided that I'm going to mount my 2 U360s underneath the CP instead of flush mounting the plate on top.  I'm wondering if there are any disadvantages to routing out the rectangular area slightly larger than the plate requires?  As I understand it, routing out the area will require me to chisel out the corners and I'm just wondering why I shouldn't just expand the area a bit...

In this link:  http://forum.arcadecontrols.com/index.php?topic=73599.msg760947#msg760947   the builder has the plate fitting nice and tight, but if I use t-nuts to secure the joy I wouldn't think a larger rectangular area would matter.  I've already drilled the holes on the top of the CP so all I need to do at this point would be to countersink a bit to allow for the t-nuts...

Thanks,

Jim