"Does blending your veg actually offer better nutriton than just eating the veg. Is there any independent evidence?"
No, it's deemed less healthy.
When you blend fruit it breaks up the cellular structure of the food so that the sugar is absorbed by the body more quickly, and for that reason the sugar in fruit counts as "free sugar" (like from the sugar bowl) if it's blended, but not when the fruit is eaten whole.
SACN on Carbohydrates and Health:
Free sugar "comprises all monosaccharides and disaccharides added to foods by the manufacturer, cook or consumer, plus sugars naturally present in honey, syrups and unsweetened fruit juices. Under this definition, lactose naturally present in milk and milk products and sugars contained within the cellular structure of foods would be excluded."