The Different Automatic Tranny Designs

Hi to all you Honda guys out there. I'm new to the forum, I currently ride and always have ridden trx300's. Two are '88's and they just keep going with minimal maintainence. It's not that i think they're the best atv out there (but I would give them the award for the most reliable). I'm looking at getting a new atv soon, I don't mind foot shifting at all but I don't want to limit my choices. Honda has put alot of time and R&D money into automatic transmission design and kudos to them for not just putting a cvt belt on like everybody else.
I'm asking about why they make 3 unique different tranny's. The hondamatic that came out on the Rubicon seems like a good design. Then they put an automotive type 3 speed w/ torque converter on the Rincon. Now they change the hondamatic on the Rancher AT to a new double clutch design with set ratios as opposed to the continueously variable. Was there problems with the hondamatic? If so then why is it still being used on the Rubicon. My question is what are the plus's and minus's of all three sytems.

Thanks,
Sailor Jerry