I only stayed at Brown Sugars for a night and enjoyed my stay. I felt safe when I got a pickup from the airport and the hostel is in an area that is a bit more quiet. Because it was low season, there were only 3 others staying at the hostel and I had a dorm to myself. The breakfast was one of the best I had in my 6 months of traveling and the dinner was also nice. The only downside was that the power was down from 12 to 10 pm but the hostel isn't really to blame for this (area problem).
The hostel is in a great location really close to the bus terminal. It's nice to relax in the hammock by the pool and although there isn't a really big common area, there is always someone to talk to in the kitchen area. I was in the dorm which was clean and had lockers. The breakfast was also really good, probably the best I had in hostels in South America!
I enjoyed my stay at San Pedro's even though I had minor inconveniences. When trying to book a tour, there was a misunderstanding, so I couldn't go to the moon valley for sunrise/sunset which was a little disappointing. The hostel is a bit outside of the centre but it makes up for this with really good facilities. The chill out area is nice, there are hammocks, mattresses to relax on and the kitchen is ok too. Don't go if you're allergic to cats though!
It is a rather large hostel with a huge dorm. It's nice that it's so close to the airport and that they offer transfers but it's not a great option if you're looking to explore the city from there. Wifi only really worked in the reception area.
It all seemed a bit unorganized when I stayed at the moonpad (note that this was in April). There was trouble getting our deposit back and also the mattresses are out of foam and not that comfortable. The common area was nice though and it was a good place to meet fellow travelers. It's also quite central and easy to get to with the metro.