Fixed Time Trial Bikes

there seems to be a bit of a trend to slam the base bars and then have a load of spacers between the base bars and the extensions. Wiggins, Bottril, Tester and upsidedown are all doing it ...Whats the rationale behind the "slam dat base bar" approach?

I like the lower base bar because it seems to improve handling in the corners and lets me stay low even when on the base bar when climbing etc. Compared with my Koga, the T3 has allowed me to drop the base bar 40mm and stick 60mm risers under the elbow pads, rather than the 20mm I had on the Koga.

As others have mentioned, there might be an aero advantage to having a short head tube/steerer and tall risers, but apparently there is also an aero advantage to picking one of two options;

1. Extensions in line with the base bar (e.g. Easton Attack TT, Planet-X, USE Tula)
   
2. Extensions well separated from the base bar
   
   

with short risers performing worse than either extreme. Roughly speaking, you either put your base bar right behind your hands and accept that the flow over it will be crap but it doesn't add any frontal area, or you put your hands far enough above the base bar that the crap flow coming off them doesn't interfere with your base, and then you need a base bar which works well in clean flow, i.e. a good aerofoil.