I'm really liking the belts, I was confused at first but now I find myself planting everything to get the top belt or dan. It is a new challenge for me and I like it.
I've stopped posting bonuses on my wall because as Raul said, the real advantage is once the level is achieved, we have a greater chance of increasing the harvest.
The only question I now have is how do we know if we get our harvest increased? I know everyone hates pop ups but a fading congratulations you have doubled your harvest or whatever would be a nice incentive, kind of like winning at slots.