The AED RDAS rocket computer is excellent. In my opinion it sits at the top of the heap of the readily available rocket computers because of the large accessory line that can be purchased as options. A great selling point is that the computer software is EEPROM based, so it is trivial to update the computers software on-line, at no aditional cost, and the factory support is superb, as is the users forum.
You don't get the flexibility and versitility of the RDAS without cost. The RDAS can collect 8 channels of data at 200Hz for 2 minutes, seamlessly hook up to a GPS unit and transmit real time data to the ground. That's a lot of data, and a lot of capacity. If you're doing real rocket research or have a very complex project, the RDAS is a great way to go, however most people don't need this capacity. (I've bought 38 RDAS units for scientific instrument packages) and they are well built and documented, and work as promised.)
On the other hand, the RDAS computer is not inexpensive, and has many great features that are not required (but nice to have) for the typical high power rocket. There are a number of less expensive flight computers that are perfectly adequate for HPR.
For example the Perfectflite miniAlt/WD costs $99, log at 20 Hz, and will fire 2 pyro events. And there are many other good altimeters from Adept, Blacksky, G-Wiz, Loki Research, Missile Works, Picoalt, and Transolve to name a few manufacturers, with varying capabilities and price tags.
The best approach is to determine what your requirements are, and what kind of budget you have, and proceed from there.
Bob Krech