Betas are always full of bugs and even CTDs - and that is true for all software, not just Trainz.'Betas are not intended for users who want to do serious route building' is a confusing statement
If you do some serious route building using a beta and encounter a bug or a CTD where your hard worked data cannot be recovered then you have wasted all that time and effort. I have certainly experienced that when I once decided to do some serious route building using a beta version and lost all the data. Fortunately it was for a new route that I had no intention of ever finishing - it was a test bed for the beta. I just thought it was strange that they recommend "no serious route building" with a beta when I thought that that would be the one sure method of discovering new bugs, which I did.