I'm in the camp of it being worthwhile as long as you really like the way the bike fits and rides and intend to keep the bike for some time. I've done swaps like this and have swapped several bikes from downtube shifters to Campy or SRAM equipment. As long as you can do the work yourself (I find it easy, YMMV) then it's only a small investment in time to swap a bike over to new parts.

I'd also recommend looking for used parts on eBay. It may require some research to verify weights, but there is usually a big savings in price that my make this project much more desirable.