We were there at the end of Feb. this year. Logistics were a problem for us even though we had 2 cars. It takes a lot longer to drive to different spots than it looks like on a map and there was only 7 hours of light.
Of the 5 runs we had planned 3 were too low on water. (started raining the day we left) The Cascadas looked like some sweet waterfalls but were a hassel as you are hit up constantly for money, which we didn't pay and didn't fell comfortable leaving our cars there unattended. The only one we pulled off was the Ahensal. It is a great 18k run. You are all alone in there and it's a lot harder than any of the river decriptions we had. There is a hotel across the lake from where the river runs into it. The owner, for a price, will be happy to drive you to the put in and then wait with a barge at the river mouth to shuttle you back to the hotel. This saves a 6K flat water crossing which would really suck as this is already a long almost continous class III-IV run. Everything is read and run except for one long class IV which can be scouted on river right.
We also got in some great beach surfing. There are several spots but just north of Casablanca was a great break.
e-mail me direct if you want a list of rivers we loked at.
t