Both the 1999 pattern and 2010 have the pertex dropliner and the para cuffs.No internal differences.Both are designed to be windproof not waterproof.We are issued a variety of layers to wear underneath the smock dependent on weather conditions aswell.
To answer the OP's question they are warm enough in mild weather when worn over a t-shirt and shirt.In the field they are usually worn with just a t-shirt or thermal top underneath.
Though not waterproof, the Irish smocks I have damn near are; I've made one my permenant winter or fowl weather jacket! I miss the neat little fold-down-seat from the earlier version in the newer ones, but a fantastic piece of kit those smocks!