The vertical straight grain wood gives better limb stability qualities that flat grain material in your core stock. Do some deflection tests with it some time and see for yourself. veneers are not an issue at .025 or less.
The part about bamboo i like is it's homogeneous nature, hardness, and tensile strength. Problem is.... Finding high quality moso bamboo flooring, or even stair tread material in laminated vertical grain configuration is tough to do any more. When Higuera Hardwoods quit making it, i switched to a totally different product i'm using now. All bamboo is not created equal. Where it comes from and how its treated for insects and manufactured in to finished material makes a huge difference. Some of that crap is pretty limp.
I've still got a bunch of the vertical grain natural color that was not carbonized and heat treated. Some guys like it, but i don't because it doesn't have the same strength or deflection qualities as the heat treated "Amber colored "bamboo. I use it for accent lines in risers, mosaics, and overlays sometimes, but wont use it in my limbs any more personally.
If somebody is interested in buying some of this natural vertical grain stuff please send me a PM.
Kirk