K-9 Mail vs. Kaiten Mail

K-9 Mail got it's first update in about a year today. It's a pretty major update.

I've been using Kaiten Mail free for few months now. Kaiten's description says "Kaiten is based on the popular open source app K-9 Mail and was built by K-9's lead developers Jesse and Chris. By buying Kaiten you not only get an awesome email client, you also support the open source version because almost all of the new features are contributed to K-9 Mail."

Kaiten seems to get occasional updates and today's K-9 update looks to bring it to where Kaiten was at a couple of months ago. The programs now appear to be nearly identical.

Is there any reason that I'd use K-9 if Kaiten is just a version of K-9 that gets updated much more quickly? Is there anything at all now that's in K-9 that isn't in Kaiten?