I ordered and built the USB I2C controller board for my Softrock 6.3 RXTX. Adding this option opens up a whole new world for your Softrock. Not only does it allow you to tune the entire bands, but also allows you to have general coverage receive capability with the rig.
It also allows external programs to take control of the radio. This is REALLY cool, as you can run Powersdr in the background and use software such as fldigi and WSPR to actually control the frequency. Fldigi logging works great too, as it can read the frequency of the radio and it puts that into the log automatically.
Another added feature is you no longer need the serial cable to key the transmitter. This is all done now via the USB port. Of course, you still need to set up virtual com ports so the additional software can communicate PTT to Powersdr.
I have been using PowerSDR v.126.96.36.199 with this new setup. This version has been designed for use with CURRENT firmware in your softrock, and it works quite well. I find the audio is less choppy with this version as well, and it's a lot prettier on the screen with its customizable skins.
Upgrading your Softrock with this little $11 board is more than worth adding the option.
On a sidenote, the other night I thought I would try some digital communications running barefoot 1 watt from the radio, and worked a fellow in Arkansas using Olivia 500/16 on 40 meters. I was running 1 watt, he was running 40 watts and was using a Flex-5000. We maintained contact for 1 1/2 hours, talking about SDR in general. Was a real fun QSO. I'm looking forward to working my first Softrock to Softrock rig, as I think that would be quite interesting.