No personal experience, Iain, but from people who use(d) it, I learnt it is
good if you need to finish large amounts of prints in the shortest time
possible - that is, after you have taken the time to fine tune it to match
your "system". As I don't do mass production I keep using test strips (and
for the tough ones f-stop timing - with a simple timer). With some
experience this works fast enough for me, and very very accurate.

Jan