Blocking an IP address from accessing your blog

I have recently noticed in one of my blogs typical spider activity. A certain IP would visit, then proceed to access only the updated articles or the articles with new comments, within seconds. For a while, I considered blocking this IP, then I decided on a better solution.

Feedburner Feed Stats–useless

I have recently decided to suppress the FeedCount, "another cool way to promote your feed" - a Feedburner option. I found that my subscriber count varied wildly, with a minimum below my email subscriber count, suggesting that there is something very wrong with the way Google has modified said algorithm after taking over this service. How wildly?