Am I worried that my keyword research might not be effective since I only look at the KC score? No. Not really. Because I tend to target only the longer tail keywords these days. I don’t go after the huge main keywords anymore. They’re too hard to rank for. But long tail keywords are really easy to find with Long Tail Pro and they are usually much easier to rank for.
It would be great if you can provide comparative analysis of this tool with Google Keyword Planner. Since you’re using this tool so you can provide best comparison. One differentiation which I understood is that this tool works for yahoo and bing as well whereas Google keyword planner works only for Google but Google being a dominating search engine, gives the highest returns, so only this reason may not be enough to buy it.