It' a great way to learn about beer ingredients. One of the best things I ever did was Mikkeller's hop series beers, which were the same beer base, but with a different single hop in each beer - taught me what I like about some hops and not others, made it much easier to indentify hops too.
Indeed! It's amazing to see how much the flavours change just by swapping one ingredient.
That series sounds great! We've got a local brewery here doing the same thing with one of their staple brews and it's always a lot of fun to see the differences.