Agree there. Yaks are not great climbers.
Also, while weight makes up a factor in rate of climb, so does DRAG.
If you have the choice of a 109K with 50% and a DT, you save some weight on internal fuel, but you are carrying more fuel than you saved in the DT, and on top of that the wind resistance drag seriously hinders you.
So you have to balance your needs. If you REALLY need to get up there fast, 100% and no DT in a 109K will help you more than 50% and a DT.
Spitfires, on the other hand, don't have too much drag from DTs. P51s and P47s do, so again it's about balancing what you want and need.