@Travelenthusiast A house reef is a coral reef that encircles the island. I think Lux SAA does have one but you have to go out to it on a boat. A lot of islands you can just swim a few metres (or even walk through the water when tide is low, if access is suitable). And yes, it's incredible being able to swim and get to the reef drop-off where you tend to see things like moray eels, octopus, massive shoals of fish and the bigger sharks (all harmless!).
We've found Purely Maldives to be a saving of maybe around £1,000 though it can be hard to compare if you choose a resort that isn't offered by the big companies. So it's not mega bucks savings but it's significant.
The service is great with PM and their access to loads more resorts is brilliant. Last year, we'd chosen a particular resort we quite fancied but it was coming in at £15k. Their agent did some research and sent us a load of options at the same spec and with the same requirements. We ended up choosing Oblu Helengeli for £10k. This was for two of us staying for 10 nights, all inclusive, in an overwater villa with a private pool and flying business class. This was in September/October too, so the same time of year you're planning on going.
The other benefit is that you have free choice of airline rather than being stuck with whichever airline(s) is associated with the travel agent. We really wanted to fly business but can't afford Emirates prices. By booking with Purely Maldives we were able to choose to fly with GulfAir, and the flights were just over £4k as opposed to around £12k for the equivalent flights with Emirates. If you do get a quote with them, just be aware that they will give you the flight costs separately to the resort cost. The first time we had a quote I was suspicious as to why it was so cheap, then realised I needed to add the two quotes together. It was still a good deal but no longer eyebrow raisingly cheap.
I probably wouldn't recommend Helengeli with a young child as the lagoon wasn't particularly good. The coral comes very close to the shore so there isn't really that big shallow lagoon with soft sand that's so much fun for children to play in. The reef is amazing and it's a lovely resort but I think it's better for adults. You could check out the other Oblu resorts though.
You might want to look at Vilamendhoo. Also on South Ari Atoll, so you could do a whale shark trip if that interests you, and has an amazing house reef just metres from the shore. We found that you could walk to it in low tide in some of the channels.
We've also been to Safari Island, which was lovely but the house reef is not quite as accessible and it's definitely less luxury than Lux. The best house reef is probably at Embudu but that's a budget resort and probably not what you're after if you're looking at Lux. Incredible reef but I probably wouldn't choose to go back as I do like a bit more luxury!
Sorry, that got a bit long... I just love the Maldives and we're currently planning our next holiday there.