210mm to 270mm is a huge jump:
Not only is it longer, it's wider. The whole blade just feels A LOT larger.
210mm to 240mm is not near the size of blade difference:
That said, I use the 270mm easily, but I still prefer the 240mm length. 210mm feels to short for me. I do use the 210mm, but not when I really want to get some prep work done.