I don’t think that $29 is too expensive for a webapp. I’m a bit worried about paying any amount for a product I don’t own and which could disappear overnight. When buying traditional software that we install, even if the company goes out of business, we still have the software we paid for. It’s obviously not the case for a webapp and given how new your product is, this might refrain potential customers.

As for free vs paying feature, I’d only give the time taken to complete the exercise and the wpm, and suggest upgrading to the paying version to have more stats.

Gotcha. The site aesthetics probably don't shout "I'm an established product and will be here long after you've paid for it" either.

By "more stats", do you mean the accuracy statistic that is computed for each practice? Or do you mean the wpm/accuracy chart that you see on the Progress link?

Don’t give them all for free. Keep accuracy and most frequent keys errors for paying customers, and incite them to upgrade if they want to know how well they scored.