773 and jtr:
High bypass engines for large commericial aircraft applications that have integrated exhaust nozzle include: the RB.211-524G/H (747/767), Trent 700 (A330), V2500 (A320 family/MD90), BR715 (717), CFM56-5C (A340), and the still-in-development PW6000 (A318). As you can see, four of the six have R-R heritage. The advantages of this configuration are improved SFC, thrust, and reduced noise. The disadvantages are increased weight and drag which usually wipe out the gain in improved SFC. The three-spool design of R-R's RB.211 and Trent is more compact, hence, these engines in general weigh less. Thus, it's easier for R-R to afford having the heavier integrated exhaust nozzle deisgn. (But the CFM56-5C, BR715, and PW6000 are two-spool engines). That's a major reason why few American-made engines have long-duct mixed-flow configuration.