The RB211 had a tricky start, but became a fine engine. But the delay in making a more powerful version, to compete with the CF6-50, hit the Tristar. Many previous non-Douglas airlines took DC-10's, so many also took CF-6 powered 747's when they became available.
An R/R powered DC-10 was offered to BA in the mid-1970s, but they stuck with the L1011.
But it's not all been good for GE, in the early days of the 757 programme GE offered a CF-6 version, rather like the RB211-535 developed from the older RB211's.
Only Air Florida ordered a few, then cancelled, GE cancelled development before the 757 flew, so the R/R engine cleaned up, apart from a few big US majors taking PW2037s.
Today, despite today's job cuts, R/R are second to GE in market share.
The Trent has a great portfolio of customers, and R/R has the best all-round range of aircraft flying their engines for over 30 years.
GE's advantage today is that it is part of a bigger industrial group, and do good deals with leasing companies. R/R cars were sold off in 1971.