I wouldn't even touch a UMC with someone else's money, but the strange thing is that for every thread where things have gone pear shaped with someone's UMC, I can point to a shop that seems to be using them just fine, with fantastic economics that might tempt one to think going with a more expensive 5ax solution is just hemorrhaging cash for no ROI.
The problem is, I can't tell if it is the arrow or the Indian in this situation. There is a shop here in Portland with a room full of 750s that is banging out very complex titanium castings for PCP that are on-point... but it is also run by the local Zeiss guy (or he is deeply involved, IDK which), so the amount of probing and complicated macro programming going on to make that happen is well outside of the capabilities of most. They love their UMCs, and they will flat out say the reason they went Haas is because they can get 2 UMC spindles on the floor for what 1 Mikron/Hermle/Grob would cost before options. I am sure that programming investment was massive, but once you have it working and prove out that the UMC can do it, you can scale the business pretty damn well.
In the end, I find the UMC situation fascinating. It is easy to sit behind a keyboard and say "You should have gotten an Okuma!" but damn... we are not talking a small amount of money between the UMC and the next step up in machine quality (i.e. the price doubles). I'm not surprised folks would read some of the horror stories, and still see if they can't get the UMC to work.