Only been to Maccas by boat so limited knowledge - my 2 bobs:
It's great but peak season can be crowded and a bit of a shit fight, even though everyone is trying to be cool (except the Brazzos). I have heard the camp is fairly popular with Brazzos. There were no surfers at the Maccas camp both times I was there due to catching it between bookings and at that stage when it was on shaky ground (management wise) and the place was empty. I hear its all ok now.
Everyone wants to surf Maccas so most of the boats stop there at some stage of their run, so unless you go in the shoulder or off season, it's unlikely you will jag it without a crowd, unless everywhere is pumping or you get lucky. The boat skippers talk to each other and are good at trying to spread the crowd around the islands when they can but it's not always possible. What's a crowd? Most i saw was 25 or so in the water, sort of manageable - but when you have 16 second period and long breaks between sets and a smallish main takeoff zone it can get a bit fidgety. You can take off from a couple of spots down the line though, which helps as you can jag a few "in-between" ones .
You can score shoulder season to yourself. We had it to ourselves for 2 days at 2-4ft in early October a couple of years ago which was good. Was also there in peak season mid July on a good swell and there were 6 boats in the bay, including 2 boat loads of Pro's on the Indies Traders: the Rusty team and quite a few of the girls from the world tour, including Bethamy Hamilton (who ripped the bag out of it with one arm). They were great to watch and to surf with, we still got waves. The Pro's were polite and had good surf etiquette but they still wanted all the best sets though, especially when the cameras were rolling - which was all the time. :?
Good thing - the reef is fairly flat, basically just a big rock shelf i think, reasonably forgiving if you can say that about shallow rock reefs? Not like Lances lefts or rights or some of the spots at Playgrounds with more coral and jagged lumps.
Also, don't under estimate KFC's (the break across the bay from Maccas). On the right swell and wind it can pump. Not the mechanical wave that is Maccas; its a little shifty like Bankvaults, but it can get good. There are a few other spots in reasonable proximity, depending on swell size and direction but we never got any of them working. it's quite a trek to Lances or Thunders from Maccas by boat.
As Maccas is generally a few hours boat ride between anywhere, once people arrive they will usually stay for a bit so expect to see boats in the channel for a day or 2 if the waves are on. It's not a swell magnet like some other spots so if the waves are smaller you can score no crowds sometimes as the boats may not make the journey.
At high tide i would think its a reasonable mal wave up to about 4ft. If it gets bigger, well, i would pick different equipment. It also sections off a fair bit when it's smaller (under 4ft).
Good fishing too. GTs, Spanish Mackeral etc plus good mud crabs... Watch the crocs and mozzies. Last time i was there the locals were warning us of a big croc that was hanging around with part of it's tail missing. Remember the crocs if you go snorkelling in the mangroves.
TAH