I've ridden a handful of 29's round the track and a lot of 21's and 28's.
I'll take the smoker and day, and twice on a Sinday, sorry, Sunday.
Interestingly though, when I was at Suzuka for the 1997 8hr they run a 250/400 4hr on the Saturday before. The race was won by an F3 kitted CBR400RR, with his team mate on another F3 kitted CBR400RR. Then came a bunch of TZR SPR's followed by the struggling NSR's.
1998 was different as it was SP spec and not a diesel to be seen. TZR's swamped the podium.