Mike:
You cannot go backwards so what ever you load can only get updated - not back-dated (huh?).  If you just go and do all the default downloads you will get the latets version.  I think if you go to the Castle site to the "Software history" ( or something like that) to get the earlier versions.

There seems to be some controversy about versions 3.13 vs. 3.16 vs. 3.18.  Crist has data (datalogger) suggesting 3.13 is better, I only have seat-of-the-pants data that says no difference.  I'm sure Crist will elaborate or you can got back into some of the software threads...

Mike,
FWIW, I am using the V2.0x version on my Phoenix 35's and 45. I am very happy with the way it works on my stunters.  I don't think there is a lot of new stuff for CL uses in the 3.0 for the older Phoenix ESC's. Now if you had an ICE version, that would be different.

I would wait for Crist to respond on the V3.x software, I think he has the best handle on it.
Eventually when all the dust settles, I do plan to upgrade my Phoenix 35's and 45. Since I have one Ice50, I am stuck with trying to support two separate versions--actually not true, since I haven't changed my older Phoenix's for quite a while now, but the time is coming when I probably would want to change some parameter--just can't leave well enough alone!

Mike,
Check you email!