The difference between my powertap, open pro 32 spoke wheel and my regular easton 28 spoke rear wheel is a little over 200g. With my 14.9 lb bike, on steep climbs >10 percent, I can easily feel the bike has a little less snap, otherwise I don't notice a difference. On hill climbs, which is all I usually do, I use the heavier powertap.

Will aero make a difference? My opinion, it's only a few watts, so unless you're racing TTs, it's not a big deal. But, if you can afford it, why not?