Andy, I saw the same change. I quickly looked up the batteries for this new supplier, and came up with a spec sheet for a bunch of batteries.
http://www.mkbattery.com/images/ss.pdf
I'm assuming that we'll be receiving the ES17-12, which looks to be the equivalent to the exide ES18-12. The battery size is the same, as is the nominal capacity. However, I noticed one key difference, being that the new MK battery has a max discharge current of 90 amps, as compared to the exide, which can discharge at (a rated) 230 amps. Is this just a case where MK is adding their own safety factor to the battery, or is it really limited in how much it can discharge?
Well, we have one day until we find out, good luck!
BEN