With J-class I was ushered into fast track immigration anyway and I found both times I've been through HAN unproblematic for getting in (getting out was a little slower, but fine). SGN doesn't REALLY have it although, as I said before, you will get moved into a priority line but that doesn't mean fast (5-mins in SGN the first time in November, 45 mins the second time, both faster than the normal lines).