Hi Ian,
It's been my experience (albeit racing shifter karts at 100+ mph), that the sequencial gear box just comes second nature - you just know what gear you are in. Maybe because it's damned important when your racing, or maybe it's just natural. Now, in city driving/traffic - I don't know - there just might be too many distractions. The up side is, it's so quick to shift, that it does not matter much. It also depends if you have to actually use the clutch once you are moving!!!