I was looking to try a Takeda Bassoon, which has been hard to locate in the USA. In my searching I looked through the Takeda website and I saw that they have developed a new wing joint which is touted to improved air flow and pitch.
Their new system switches front tone holes 2 & 3 and makes them point up the bore. This ends the tone holes in a stretch too wide for a natural finger spread and so keys have been added.
Whenever I play on a bassoon that has the left hand third finger tone hole key added I notice a big improvement in my technique. So I would be curious to see what adding two keys would do.