Modern IWC watches do have gold plated movements anymore, but there has been a time slot from the 70s to the 90s when IWC produced some gold plated wrist watch movements and "modern" pocket watch movements as well. Older pocket watch movements were mostly gilted.
Although there is no quality difference of those movements, I would prefer gilded calibers..
A gilded movement simply looks much more valuable, at least my taste.
Some examples:
