You don't need an upconverter to receive HF on the version shipped by rtl-sdr.com; it supports it via direct sampling mode. I've listened to plenty of shortwave broadcasters and hams using it with a random wire antenna.

I did recently get an rsp1a as an upgrade once I realized how much fun I was having. It seems better at rejecting noise but otherwise isn't that different than my rtl-sdr. I need to get a windows install so I can use sdruno instead of cubicsdr, though.