Jrdwyer,
I can speak to teak - we have several thousand trees of it. The young wood is quite stable as well. It is due to the fact that it grows where it never really stops growing (no winter). In some areas (like Guanacaste here) it is dry for 5 months, it would be interesting to see if that has more of an issue.
Recarding decay resistance, usually not until 12+ years will a teak tree have developed enough oil to be weather resistant.
An interesting note on that. The amount of heart wood is dependent on the richness of the soil, not the how slow it grows. In our zone we have a very good percentage of heart wood - and very fast growth. I know places with slow growth and almost no heartwood. (around Los Chiles for example)
I hate to tell you Harold, you can't plant teak up where you are - you are too high. The top of the range is considered to be about 1,000 feet, you are closer to 1,500 feet. Or, you can plant it, but don't expect good results.
You are absolutely right - if you want to save the rainforest, plant trees in plantations (but don't cut down rainforest to do it.)
Since we are a "Contributing Member Shameless Commercial Link" (home page) perhaps it is appropriate for me to comment that we do sell trees and grow them for people (Pete with Logrite is an owner) and I will make an executive decision and say that I will donate 5% of all purchases that mention Forestry Forum to the forum.
We are getting growth rings of 3/4" on our fincas. I know that stays that way because we harvest teak from fincas near us and they have been like that. We are finding trees that are nearly 3 years old are averaging between 4 to 5" in diameter as well (and between 30 to 40 feet tall).
Den, where did you see this teak? How long did it take to dry in your vacum kiln?
Unfortunately, I am running away for a couple of days, but I will be back Saturday, but if you reply really quickly I might still be here. If I don't respond, I will in a couple of days - if the big boa doesn't get me.

Fred