Mike,
As all the wise words already offered by the rest of the guys, it is purely a matter of personal preference.
I have a new R500 Duratec on order, which should be delivered some time( i hope) in September.
I went for the Sequential box, because it struck me that it was a must have option with the new R500.
I have previously owned and built a Supersport 1800K, with a five speed box, which suited that car as I used it mostly for touring.
My last Caterham was an R400 with the Six Speed box. I used that car mostly for Track Days and Sprints, so the Caterham Six Speed was the logical choice.
However from the get go, I was never happy with the Caterham Six speed, the selection was never slick enough in my opinion, and it was easy to miss gears especially on track days, using full bore up shifts.
In addition my Six Speed went pop in a big way, and was totally rebuilt by the great guys at road and race transmissions, at a cost of thousands I have to say!!
It was whilst rebuilding the gearbox, they found that my gearbox, had a part missing from the motion shaft, that was never fitted at all, explaining the reason why it always felt so bad to change!!
Once road and race had fixed it, it was a massive improvement, and I am sure Mark Williams, who now owns my car will vouch for that too!!
On my new car, the final decider for me on going sequential was the power and torque handling.
The new Caterham supplied Quaiffe QBE60G, that is coming in my R500 is rated to 450BHP and 400 lb/ft, so with my car coming with 265BHP, I figure there's room for future upgrades.
I am sure if you asked the right person at Caterham, try Nick Potter at Caterham Midlands, they would supply a new Sequential with your R400.
Best of luck, and when my comes feel free to drop by to check it out!!
Nige.
Nigel
R500 CP - New 2008 Duratec R500