newnandawg - Northern California on the peninsula south of San Francisco.
Hortstu - Certainly a drip irrigation system would make life easier if you are growing more than a few trees. Those 2 mixes, when used correctly, will certainly work well. There are big, commercial operations that grow fruits & vegetables in straight perlite. Pure perlite requires a fair bit of infrastructure, but it can be done & done well. So, you can make a lot of things work well with enough effort. As much as everyone is looking for a perfect media recipe, I do not believe one exists. After a LOT of research and a modest trial comparison to the 5-1-1 mix and a couple of others, I chose a different mix. As is pointed out in the quote above, both those mixes require more frequent watering than I care to do. A drip irrigation system certainly makes life somewhat easier. The danger of putting a drip system on a timer is timer failures. To be clear, I use a drip system for my plants. I have never tried a timer. I talked to a bunch of people who have used them and every single one of them said not to use a timer. That advice is always followed by their personal "timer failed" horrible, disaster story. That said, I am betting someone out there has a timer that has gone 10 years without a hitch. The point is that the type of automated system most folks on this forum might afford is very likely to have a very limited life and fail right when you are depending on it most. The subject of water movement & utilization in potting medias is actually pretty complex technically. In my opinion, the best, current scientific text on growing in soilless media is this text:
http://www.amazon.com/Soilless-Culture-Practice-Michael-Raviv/dp/0444529756/ref=sr_1_2?s=books&ie=UTF8&qid=1350623483&sr=1-2&keywords=soilless+media
Be forewarned that this book is HIGHLY technical. Lots of math. Probably a third of it is devoted to water. Happily, there are mix components you can try out that retain water better than the mixes you mention and have the physical attributes of a good soilless media. If your media has adequate air space, total porosity, container capacity, available water, unavailable water, bulk density, CEC and pH, you will have healthy plants given proper nutrition and water. I'd spend my money on a good pH/Electrical Conductivity meter before a timer, drip irrigation system.
Good luck with your trees!