Generally speaking, any time you laminate material you strengthen and stiffen the end result. This is usually a Good Thing both mechanically and economically, but you'll get mixed reviews when it comes to instruments made of wood.
In stringed instruments, the effects of various wood species, densities, grain orientations, construction, etc. are all variously subtractive. That is, a softer or more porous wood will absorb more high frequencies than a harder or denser one, regardless of how you get there. No wood (or other material) adds any frequencies, so the idea that some woods sound brighter or darker is false: they don't have a sound. They're parasitic. The frequencies are generated by the strings where the energy is put in, and entropy drives it all downhill from there. Traditional magnetic pickups only pay attention to the strings; they can't hear or sense what the wood is doing. This is why the same guitar will sound dramatically different acoustically vs. electrically. But, since the wood is absorbing energy from the strings, it affects how long and true they vibrate, so the pickup sees an effect after all.
Knowing all that, what can we say about fretboard wood? We know laminating woods make them stiffer, so it follows that laminating them with stiffer woods will make them even stiffer. So, the end result is the neck doesn't absorb as much vibration, which in the guitar world means "brighter". That is, fewer frequencies have been absorbed.
This is not a Bad Thing. You can filter out frequencies you aren't interested in electronically. But, outside of synthesizers, you can't create them if they don't exist in the first place. So, in my opinion, it's better to have a neck that doesn't absorb frequencies so you can throw them out as circumstances demand rather than have one that doesn't create them at all. You never know when you might want to sound accurate or articulate.
This has an advantageous side effect: very dense hardwoods wear better and have better playability. So, Ebony, Ziricote, Bloodwood, Pau Ferro... have a blast!
