2nd BTB units have been a "problem" on our COLORPRESS machines for about the last 1.5 - 2 years. They are good for about 30,000 - 60,000 prints. Then......... fail.
As for 2nd BTR in Versants there are new ones available being tested in accounts that have poor life. There is also new nvm scripts released a few weeks ago that improve the current one.