Do you think I could replace the pear with rhubarb for a springtime take on this recipe?

The pear almond recipe sounds delicious, and I love your springtime version using rhubarb. I think it would work well, although the rhubarb is much tarter than pears. On the other hand, there is quite a bit of sugar in the cake. I'd give it a try--worse case scenario is that you would need to serve sweetened whipped cream if the cake isn't sweet enough.