Block lightening seems like a lot of work and cost trying to save 25-30 pounds? I'd gladly eat salads for a year to lose 25 pounds off my backside if I had the opportunity to build one of those blocks. Building to the extra HP handling potential would make up for the additional weight in short order.
If you are in a competitive class of racing every ounce counts and 35lbs is a lot. Those programs exist because some racers demand it. It's not for everyone.
Like I said, make enough power and it won't matter how heavy the block is. Or find other areas to shed the weight.