I wouldn't use split. It's much easier to define what you want to keep:

$string = "<*2>FOO<2,1>,<*3>(SigB<8:0:2>,BAR),<*2>Siga<2:0>,Sigb<8,7,6
+,5,0>";
@parts = $string =~ /((?:[^<(,]+|<[^>]*>|\([^)]+\))+)/g;
say for @parts;
__END__
<*2>FOO<2,1>
<*3>(SigB<8:0:2>,BAR)
<*2>Siga<2:0>
Sigb<8,7,6,5,0>
[download]

This assumes no nesting of parenthesis/pointed brackets.