Don't fix stuff that ain't broke!
Just for the record, it is "broke".
There are at least 3-4 bugs, of which I have direct knowledge, that were fixed between 4.3 and 6.1. However, I'm not getting into a debate about how it doesn't matter if Phil doesn't see the bugs at present. Nor am I going to detail those bugs here, other than to say that they are operation-affecting.
One should, however, be aware that if one of these bugs does surface down the road, that it's unlikely that MTH is still providing support for software that was released more than 4 years ago. I expect that MTH's remedy (and it would be mine, as well) would be to advise updating to the latest DCS release and then seeing if the problem persists.