Well, I've been down that path way back. I was using a StarTrac Vbike when I got into cycling. Short story, the resistance just isn't the same. The best use of a trainer is intervals. It just makes the time more economic and less boring by being able to do a shorter workout. I now have my original road bike permanently sitting in a Kurt Kinetic Road Machine. I use it mainly for sprint track based efforts.
For the money, a trainer with your bike in it will be much more useful. I would rate the KKRM as one of the most economical of the power based trainers due to its proven reliability and correlation to road output. You can function just fine with their graph and a speedo for power output or you could pay the little extra and get the add on sensor to display the output details on an apple device.