I don't know if what I'm going to put down here will help you but maybe it can build from here. The way I see it is that wicking beds have several purposes
1. To act as a water storage reservoir
2. To wick water up to the plants.
3. To inhibit weed growth - by keeping the surface of the soil dry.
4. To conserve water.
If you look at some of the better wicking beds you'll see them using milk crates and ground cloth to provide a large space for water storage capacity. The bigger the reservoir space, the less often you'd have to add water. Food and Fish builds good wicking beds and DecalsbyJT has some nice ones in his thread as well. There have been lots of good ones, I can't keep track of them all but there are others.
If you don't provide a decent size reservoir and you don't have an auto top up valve you'll be filling the reservoir way too often.
Personally I wouldn't want a really shallow wicking bed. As a raised bed I think it would dry out too fast on hot days and would be soggy on cold or overcast days. If the bed is too shallow and stays wet too long I think you'll find weeds will grow more easily. They'll be times when it rains and you'll get some but when it's dry the seeds have a hard time germinating. For me this part works well in Summer but not as well in Winter when it rains a lot. In Winter, I get weeds sprouting on paths, in 12" deep rock with no soil
.I would do a few things differently if I were building these again.
1. I would make them smaller - easier to fix leaks and they warm faster in the Spring.
2. I would use a better liner - one of the beds sprang a leak and changing a liner in a 3 x 15 wicking bed probably isn't going to happen any time soon.
3. I wouldn't use rocks for the reservoir - I couldn't find milk crates used and didn't want to pay for any but rocks are a lot of work.
4. My wicking beds rely on ground cloth as the wick and while this works, at some point I envision this breaking down. Putting sand in like DecalsbyJT would have been a better choice and I'll probably have to insert some wicks with sand in the future.
Other than these I'm very happy with how they've turned out and they save me lots of weeding.
Cheers
What is the total height of your wicking beds? Do you mind sharing how you are plumbing it to flow and ebb? Is there a thread with pictures? 
