Well, I'm not sure how this fits to the "lighter" point, but a Buckling Spring Keyboard is definitely worth a try. It might not be as light as blues, but the tactility is far superior imho, and the click isn't as annoying as the blues click. I think blues sound like shaking a bag of legos, compared to the metallic click of the Model Ms. You might find a used Model M on ebay, that won't be too expensive and if you don't like it, you can simply sell it off for the same amount of money and don't make any loss. Buckling springs might be stiffer than blues, but they still don't feel as tiring as an average rubber dome.