I think it might help fellow travellers to know about our experiences with Chimu Travel (to-date). This might turn into a very high level blog (as I will update it with good and bad experiences). My wife and I are at the start of a 4 month tour around South America (Argentina, Uruguay, Chile, Bolivia, Peru, Ecuador/Galapagos, Brazil and back to Argentina), and when I first booked our tour of South America with Chimu Adventures Ltd, I found very little feedback on any website other than Chimu's own.
We were concerned paying out a huge sum of money in this economically horrible time that Chimu may go out of business, but I presumed that as Australia is booming, an Australian travel company would be relatively safe, so made our bookings.
We are now three weeks into our tour (although the first two weeks was a stop over in New York), but since we have been in South America, every detail has run to clockwork (other than a self induced hic-cup of getting off a coach at the wrong bus station!). All pick-up's have been waiting for us when we arrive and the vehicles have been unexpectedly superior to every day taxi's, great cars with a driver often in a suit.
We were a bit dubious about South America before we started as our tour is lengthy and complex, but so far, I cannot fault the arrangements made by Chimu Adventures.
Also, on the positive side, when we first started finalising the trip (at the Destinations show in London in Feb 2011), we made contact with 4 companies. Chimu was by far the most reasonable (thousands £'s cheaper than the others). Gemma in the London office was first class with her fantastic knowledge of the countries. Just to let you know we are post children travellers so not backpacking but in boutique and 2/3 star hotels.