I won't dispute that you've been working with computers for some time, however your posts are extremely inaccurate.
For starters...
Only one of these that you have listed is part of our DLC system. Specifically the S&C pack. As neither the Marias Pass or Roy's Trainz routes are available through the new DLC system, they will not need to be re-downloaded. At this time, the only DLC's that you will need to re-download (if you own them...) will be the 'official' DLC packs (Those that use a '.exe' installer, and a serial number that appear in the 'configure trainz' options).
I only know of a small number of people who have experienced issues that actually require a re-install of Trainz. I think it maybe 5-10 people so far? Note, this is where we have recommended a re-install, or would have recommended a re-install. Out of the total number of people who have downloaded it (and so far, it's only been announced via these forums; so those who have downloaded will have had plenty of opportunity to download), this is a very small number.
Actually, I've found only a small amount of content in my TS12 that was faulty, at least of content that I actually use. Mind you, most of mine is DLS content, and fairly recent content as well. Those that are faulty should be fixed fairly quickly as part of the DLS clean-up...
Our point is that most of your comments are relatively uninformed assumptions based off comments on the forums, the majority of which we've actually resolved, or are working to resolve. Unless you have installed SP1, you really can't accurately comment on what SP1 actually does.
Regards
No offence, but I am not into beta testing software anymore, did that back in my flight sim days for a few years, and don't presently have the time or interest. When the dust settles, after a couple of months, and the threads outlining problems with SP1, subside a bit, I might consider trying it. Right now, everything is working pretty well on my system, so "If it ain't broke, don't fix it" is the way I am going to proceed in the near future.