Hughie, the handles that you speak of will probably never take over from wooden handles, as they cost money (and don't suit some people) however, they do have many advantages.(generalized)
1.If your traveling there is no wood to worry about (customs etc)
2.You can remove the tools for sharpening.
3. they can be lengthened when needed (some designs)
4. they can be filled with lead etc (for vibration/balance etc, very much a personal preference)
5. generally robust, so may not break like some wood 'could' ( heavy work)
6. some have foam grips for better grip and comfort.
etc,etc
Then if you talk about collet handles they can have numerous advantages.
Particularly if the 'right' collets are used. (some can be 'limited') One brand of handles for example use ER collets which have a 1mm tolerance, and the collets are available in 1mm increments. So you can fit 'almost' any round tool in the handle.
Collets are great if you don't want to damage the tool shaft (like grub screws do) and are much quicker when changing tools eg: when hollowing etc.
There are too many advantages to list here.
I am interested that you mentioned Vermec,(beautifully made products IMO) also inquire about the new Kelton handles. (just released)
There are numerous manufacturers, however I don't know if anyone has ever compared them all against each other.
I hope this helps.
Glenn