I would say reduce bitcoin-qt. I'm not as much worried about the 10gb because of the size of harddrives these days as much as I'm worried about the large amount of time it takes to download for someone interested in starting up. It took me several days to get it downloaded and I feel like in the future that can make people less excited to do BTC.
Hrmm. I think we have come to the point that your average user should not be using bitcoin-qt. As much as there will be pruning of the blockchain in the future, we are constrained by the fact that we have to download and verify the blockchain if we are to use bitcoin-qt. While some optimization can be done, there will be a limit and it will still take some time to "boot up" due to the design nature of the software.
Hence I feel new users should a non server trusting thin clients instead. Yes, the security might be reduced but I feel at this point in time this model is decently secure. Multibit comes to mind as a great choice; It's easy to use and fast.
