Actually there is a difference. Silver plate is considerably more durable than lacquer, or so I've been told. The many vintage horns with 95% or more silver plate remaining seems to bear this out.
Also a re-plated horn isn't devalued as much as a relac. Maybe because the re-plate adds metal to the horn, albeit a very, very tiny amount. Probably in reality there isn't a huge difference if, and only if, the relac is done with minimal buffing, which isn't always the case.
Finally, if you like the look of silver or gold plate, that's also a factor.