I like doing the switch on the way to SYD as there's 4 hours between the 380 landing in SIN and the 777 departing for SYD so plenty of lounge and leg stretch time. Coming back on an Avios booking (so TPs irrelevant), we're doing the 777 through flight all the way. The risk of a misconnect for a 20 minute longer transit in SIN isn't worth the risk to us.