A very positive experience with the new tool. I went to Miles and More-->Account-->Current bookings. Then I scrolled down to "Enjoy more comfort with an Upgrade Award (for miles/eVouchers)/Book online" and was taken to this page: https://www.lufthansa.com/de/en/prof...search-flights
I then entered my flight details and the system offered upgrade options, either with miles or vouchers. I selected evouchers and the upgrade was confirmed instantly from business to first class.