DCS v.4.0 has been released by MTH and is available, as always, as a free download from their web site. It has lots of nifty new features, which are documented on the DCS Revision History page of my main web site and I think that once you try it, you'll really like it. I find that I use the new quickset speed control a lot, and being able to clone the remote is very, very handy, especially when you have a lot of locomotives as I do! But now for the caveat.
Based on my own testing, it appears that there is a bug which causes the Variable 1 track to lose both voltage control and DCS signal, but only on the original Rev. G model of the TIU. The Rev. I TIU and the Rev. H1 TIU are not affected by this bug. As a reminder, the Rev. I TIU has a sticker on the bottom that says Rev. I and the Rev. H1 TIU has a sticker on the bottom that says Rev. H1. The Rev. G TIU has no model designation sticker on the bottom. If you have the Rev. G TIU and you use the Variable 1 channel, I would recommend not upgrading to v.4.0 of DCS quite yet. I expect that v.4.01 which fixes this bug will be out shortly.
::sigh:: At least it's a software-based system where such a bug can be fixed with an upload of corrected software. Helluva beta tester I am, not to catch this for MTH before they released the software.