+3 on the Despiau bridge wing. It's a decent surface area and nice and tight so by removing a little wood an making a "flat" spot on the arch of the leg it is pretty easy to get a good snug fit for a bridge wing piezo.
Here's what my Despiau looks like on the wing where I mount a K&K bassmax (not shown):
You can see the slightly flattened arch and the shape of the wing. It works great for the K&K.: