Hooray!!! Now at least you have a properly working replacement for the DCS100 that Digitrax has discontinued making and supporting.
But, that is with the DCS240 restricted to using no more "slots" than the old DCS100.
I am still wondering if the DCS240 can work properly with the slots between 120 and 400 enabled, provided that only Digitrax throttles that are enabled for those higher slots are all that get used.
You have the perfect system to test that.
And, if it does work properly the higher slots with the Digitrax DT602D and UT6Ds, then to check with your TCS throttle. If that works, then see if it breaks when your UT4 is used. (I expect the UT4 will cause the consist-breaking problems to come back.)
I understand that is a lot of work to investigate, so no hard feelings if you don't want to go there, especially now that you just got it working for you as is.
If not now, but you get the urge to use those extra slots later, check back with this thread. By then, we may have the answer for your. Or, if not, we would like to participate in the experiment when you get around to it.