I thought of that too, but it does have some problems. Eval-string is very cheap in that accounting. print 'a'.'b'; is cheaper then print 'a','b'; (the former constant-folds to print 'ab';).
This is why print "a"."b"; is faster and more efficient than print "a","b";. I think it is *good* to have the former be less points.
When not using constants, it's a different story: print "a".$_; is 9 concise-lines while print "a",$_; is 8.
I think eval-string should be avoided anyhow, in a golf contest like this one.