before begining to install a new web with joomla 1.6 and trying to install template as iridium, do you know if there is some compatibility issue with new Joomla version ?
I would download 1.6 and install it locally, then poke and prod with it until you are thoroughly intimate with it. I am still going through it and will most likely be for a long time before I feel comfortable using it with clients' projects. Just remember, newest does NOT always mean the greatest. What IS golden is when you can ascertain the best solution for your requirements.
Also, when RT begins reverse release of their temps in 1.6 I'd start to then dig into Tachyon 1.6 and start customizing the living daylights out of it, pushing the limits if you will. This is the best way to dig down and see 1.6 ways, RT is very good at doing things in a proper manner.
Hope that helps
Jeff
When someone is impatient and says, "I haven't got all day," I always wonder, How can that be? How can you not have all day?