Hi, Chris and Lynn. An interesting question. I had never thought about using hardware cloth plus a soil barrier.
So far, in more than 50 containers, no problems with any of the semps and jovi's rotting. I did make sure to put a number of holes in the bottoms to avoid this problem. With the wood being able to retain some moisture, I think it gives the whole container an environment more like the ground the container (can I say pot, even though it has square corners?) sits on.
However, another issue arises. Given that I hand cut the sides, there is a problem trying to assemble a reasonably square container without a bottom, due to angles of the cuts and trying to hold together a couple of pieces of wood while you manage a nail and hammer them. With two people that should not be a huge issue, but I think something like a table or miter saw would be necessary to get the angles of the cuts good enough to provide a stable container without the reinforcing bottom. Also, would you be able to find stainless steel staples to hold the cloth in place? I use hardware cloth of various sizes for sieves and have to re-staple them periodically when the staples rust out. That would be hard to do with a container a couple of years old with established plants.
Still, I LIKE the idea of the "hardware cloth/soil barrier" bottom. Perhaps some corner reinforcement, a second pair of hands and a better saw would make a good product.
I am not making wooden pots anymore, since I have now moved on to larger containers (~12"x8") by recycling and converting plastic buckets for my plants. I am fortunate to have a free, reasonably reliable source for them. I currently have more containers than space to put them.
Here are a few pics showing the plastic containers I am now making, as well a portion of my Pacific series collection in both the wooden containers and one in plastic (Pacific Country Cousins). The lower left hand corner of the third pic shows a container that my dad made more than 20 years ago.
Recycled plastic square bucket cut down, drainage drilled and painted using plastic paint.
Some of the S. Pacific series in wooden and recycled plastic containers.
Here's a hint for those of you who want to try recycling the plastic buckets. Be very careful with the cutter. A repeated light touch works best for cutting them, don't try to force it our you will cut yourself and make poor cuts on the plastic as well. Use a metal straight edge for the initial cuts and be sure to measure. 6" from the bottom makes a nice container. Total cost for the plastic container (per container) is about $1.00 for the plastic paint. I've had some of these unpainted buckets out in the sun and UV for years without too much degradation, but use the paint to block UV and make the containers look more acceptable. I expect to get 10 years or more out of them and they are thick enough to survive occasional hits from the weed eater. They are also "green" since they are recycling what would otherwise be waste in our area. Not a bad size for semps, either.
I would think the wood bottom would soak up to much water, thus keeping the soil wet. I think I would use the hardware cloth. 
on the containers! 
Although now that I've read these posts, I'm considering poking a couple of holes in the seams (the wood I used for the back is oak I think - from an old bookshelf, the sides are pine) 
chocolate almonds! 
