I did my first doubles to make it easier to bend tight cutaways in tough woods like Maple. Later I found it had a very positive effect on the tone and started doing it on regular models. I've only done 6 or 7 so far. I have a captive audience of great players and experienced retailers at the store where I sell and the general consensus is the doubles have been a very positive thing. I got the idea from reading about Tim McKnight's stuff and the Bogdanovich classical book. Howard Klepper had some good pictures of his laminating jigs somewhere.
I have a hard time describing tone but these seem to be louder and exhibit a little more lively less muddy feel with better tonal separation if that makes any sense. Anyway it's been viewed in a very positive manner by the majority of players. I plan to keep doing it especially with LMI offering lower grade thin sides for this purpose. Unibond 800 is a great glue. It dries hard like glass and has no water in it.
Here is the Bird's Eye just off the laminating form. It ain't goin' nowhere, you almost don't need a mold.
Here's a clip of one that is at the store now. They hype it a little which is a bit embarrassing as this is certainly nothing new or revolutionary.
http://www.thepodium.com/p-17650-kenned ... op-om.aspx