Update: I'll say it plain, most carpet pad upgrades are a waste of money
Last month a homeowner in Reno paid me $600 extra to swap her 6lb pad for an 8lb one in the master, and I swear you could not feel the difference walking in socks. The pad under your carpet does about 10 percent of the work and the carpet face does the rest. Unless you have pets or heavy traffic, put that money toward better carpet. What pad weight do you actually push to customers?