In the 2 days since the change, there were 9 more sales and 7 more active installs, which is slightly less than the previous 2 days. So removing the free version actually reduced sales a tad (within this very limited sample size). Why is that?
What you can't tell from these figures is the number of cancellations. If I'm reading this right, the totals above, which come from the Market Developer Console, reflect sales after cancellations. Over in the Google Checkout order inbox I see that there were 4 cancellations today alone (compared to 3 sales that were not canceled). That makes sense, because without a free version the only way to try it out is to buy it and then return it if you don't like it.
One could theorize that a few people who might previously have tried the free version and then gone on to buy the paid version hesitated at pulling the trigger when there was money involved. If this bears out, then Android developers may still need to produce Lite/Free/Demo versions just like iPhone developers do. I was hoping that wouldn't be necessary given the extra complexity of maintaining two versions of your program.
What's next? Well, what do you think would happen if I dropped the price of the Pro version to zero? That's got to have some kind of impact, doesn't it? :) Just to be fair, if you bought the ReTranslate program between February 20th and March 4th and would like a refund of the price difference, email me your order number and I'll be happy to take care of it.