At that price range, in house or ETA based, probably makes little difference in terms of quality and use. The Tank Solo, is a very nice watch and a great value, but it's movement will not be as finely finished as the movements used Cartier's more costly pieces (which can use either in house movements or very high quality movements from Piaget, JLC, or F.Piguet). In addition, if one can get a good deal on vintage one with an ETA movement, there is nothing wrong with a watch powered by an ETA movement. It's a good solid workhorse, that will provide many years of trouble free use. Many watches from Cartier's past such as vintage versions of the Santos, Tank Francaise, Pasha and others have used ETA movements.