ever TRIED it?
trust me, adding a tag to the ini and testing it file costs far less time than posting such questions here and waiting for serious answers...
Unfortunately (as was said at PPM) IsBigLaser=yes doesn't do anything in RA2/YR. The PrismSupport uses that effect, but to my knowledge it is hardcoded into the prims support logic.
I could be wrong, of course.
but (via hacks) I tested BigLaser, and it works fine in YR.
I planned implementing it into the patch, but I don't hurry with it since it's not too important.
it would be nice, i tried it for my lestrech tank, and it never worked.
something else i want to see if to be able to include both islaser and istesla on the same weapon, that way my lestech tank will look right(a tesla bolt in a laser beam) currently, its a laser beam with tesla shards.