Of course you get smoother shifting, but how much so? It appears that the proposal here is to go from one 11-34 to another. If the proposal was from a 9sp 11-34 to a ten speed 12-25, now that would really smooth things out. BUt my point would be that nearly the same change wold be had by going to a 12-25 9sp. I took the 11-34 off my Cdale starter bike and have a 12-23 now. Same 9sp gruppo. Now that really smooths things out and I can actually use the granny gear now. Cost me nothing as I had the cassette. I've got DuraAce ten sp on my racing bike and there is some value to the updated stuff. But I don't think you're getting a lot for your money making this sort of change uless the drivetrain is worn out and needs replacing anyhow. I don't really think most folks need a 11-34 cassette, unless you're hitting some really big climbs. In racing, changing your gearing is as common as changing your tires, maybe moreso. I gear the bike for the course every time by changing the cassette. Same can be done here: buy a cassette with a better range for your uses and see how it goes. Cheaper than STi levers....