The straight answer to Peter's question is that we just don't know, but that it's a reasonable assumption. Raff himself thought that No.6 was an advance on No.5 and if you read Avrohom Leichtling's essay on the work at the Raff web site you'll see why. As I'm on holiday just now I can't really write at length on this, much as I'd like to, but Ilja is certainly correct that Raff didn't seem to subscribe to the view that everything built up to the finale. Rather that the slow movement was the emotional centre of the work and that the finale represented a relaxation of the tension.