maybe upgrade to the DS64's or 52's both of which have CDU's built in which may help things along. another thing to check is the actual voltage feeding the decoders you have?? it may be a little high or low?
I have been using the DS51K1 which were designed for use specifically with the KATO turnouts.
The DS64 is supposed to throw the Kato bi-polar switches. Do you have the DS64 set up to throw the type of machine you are using? I have one that is throwing Peco switches for several years. I would like to use them with Kato switches on a module i'm building, so if you find out what is wrong let us know. You have used 13 DS64's? Thats quite an expense.
I have an HO layout with a Zephyr, all KATO unitrack with 8 turnouts. I'm using the Digitrax stationary decoder specifically for the KATO turnout. My failure rate is over 50%. The decoders are burning out when the turnout is called up to either throw or close. To date I have installed 13 decoders. Two people very experienced in DCC and Digitrax have verified the installations as correct. Any one else heard of these type failures in this many decoders?