Yes, MEL F is much much smaller than SYD, but that has not usually been a problem given F cabins out of MEL (when QF had any) and even OWE demand. Yes I've experienced it busy to nearly full in the mornings, but other times more or less deserted.... it definitely does the job imo. I have had to sit at the restaurant counter once or twice for brekky back when EK had its morning tag to AKL with pax coming in for QF and CX departures ahead of the QF93 to LAX but even then that was more because I didn't want to take a table for just one, and happy to sit up at the bar. it was fine (plus service was great!)
Since it's now basically an OWE (inc QF WP/P1/CL) lounge with no actual QF F pax it's interesting to see if that's changed any aspects of the lounge. I'll be there in Feb ahead of the QF21