Hi James I suspect it is difficult to generalise about reliability. I drive with mechanical sympathy until up to temperature, then pretty much drive it like it is stolen. My 6 speed, to date, fingers crossed, is fine. A very good friend and all round top bloke, who respects his lovely R400D, had a 6 speed gearbox melt down on a sensible blat last year. My advice is, as long as it has not been raced, and it works nicely, don't worry. Buy it and enjoy, if it needs a rebuild at some point, ces't la vie... Julian ps - 6 speed over 5 every time for me!