Several of the quants I know started out in model validation. Internal moves in my firm have as of late, however, become highly politized affairs: There are minimum terms one must serve in validation (two years or so) before a move would be accepted and even then I've seen moves blocked from the head of quant or model validation due to office politics. This leaves everyone in a bad mood, and the people who wanted to move, often will, but to a different firm, and so tbe company loses a good employee and wastes a lot of time and money on recruiting externally.
The main skill missing from people who do move is programming as at the firm I work at programming is even actively discouraged in the validation team. This can make it more difficult to move and hinder one's career, so while in validation you do learn a great deql about the models and such, do try to keep abreast on coding and to an extent on what exactly the business is doing (types of trades, their volumes, why are they being done, how will they actually hedge them etc).
